You’ve got your Raspberry Pi all hooked up and ready to run, but nothing happens when you connect the power. Something, somewhere, is wrong, but what? And what can you do about it?
Here is what you need to check to troubleshoot a Raspberry Pi that won’t boot.
1. What to Do if Your Raspberry Pi 5 Won’t Boot
As the fifth full generation of Raspberry Pi boards, the Pi 5 is more reliable than earlier models. However, it remains susceptible to some common issues.
You should be able to identify most issues with booting from the LED status. Unlike previous models, the Raspberry Pi 5 has a single, bicolor LED that can illuminate in red and green. Red means the PSU is connected, and green indicates that the SD card/boot media is active.
If the LED flashes four times slowly, followed by five fast flashes, the Raspberry Pi 5 has a fatal firmware error. Four short flashes and six fast flashes indicate a power failure. Both should be reported to the vendor for a replacement.
Use the Correct PSU
The Raspberry Pi 5 requires a 27W USB-C power supply. While some owners have reported the Pi 4’s power supply is adequate, this tends not to be the case once peripherals are attached.
We understand that the Raspberry Pi 5’s power supply is difficult to buy in some territories. We recommend buying the official Raspberry Pi 27W PSU rather than risking a third-party device. If you have to use a third-party charger, use one rated higher than 27W.
Is the Boot Device Attached?
Like earlier versions, a Raspberry Pi 5 can boot from a USB device and microSD. Like the Raspberry Pi 4, it can boot over Ethernet; in addition, it can boot from an SSD connected over PCIe.
However, if the Raspberry Pi 5 isn’t booting correctly, and the PSU isn’t at fault, ensure the boot device isn’t responsible. With an increasing number of boot options, this will take longer than it might with an early model.
Also, only Raspberry Pi OS Bookworm is supported by the Raspberry Pi 5. Older versions will show an error message on the boot diagnostic screen.
Are You Using a Working HDMI Cable?
Another problem Raspberry Pi 5 owners encounter is boot failures due to HDMI cabling. The best option is to avoid using micro HDMI adapters and use a high-quality Micro HDMI to standard HDMI cable instead. Doing so avoids the risk posed by poor-quality adapters. The official Micro HDMI to HDMI cable is durable and affordable, but any good cable should work well enough.
2. Raspberry Pi 4 Not Booting? Try This
Three issues can result in the Raspberry Pi 4 not booting or appearing not to turn on.
Raspberry Pi 4 Power Issues
Like the Pi 5, the Raspberry Pi 4 uses a different power supply unit (PSU) than older models. Power is via a USB Type C connector, preferably from the official 5.1V 3A PSU. As with older Raspberry Pi models, a mobile phone or tablet charger is usually inadequate if it can’t supply up to 15W.
Raspberry Pi 4 Not Booting and Red Light Showing?
The Raspberry Pi 4 requires a fresh installation of the latest Raspberry Pi OS. Regardless of your preferred Linux distribution, you’ll need a version compiled for the Raspberry Pi 4 and released post-June 2019. The official options are Raspberry Pi OS (64-bit), Raspberry Pi OS (32-bit), and Raspberry Pi OS Lite.
Operating systems compatible with older Raspberry Pi models will not work reliably with this device. An older or unsupported operating system will result in a red LED light when the Raspberry Pi 4 is powered up. It simply won’t boot an OS that isn’t designed to run on the computer.
A fresh installation of the latest Raspberry Pi OS will solve many booting issues with the Raspberry Pi 4. The Raspberry Pi Imager is the best way to install an operating system on the device and always shows the recommended version of Raspberry Pi OS for your model at the top of the list.
Raspberry Pi 4 Has No Picture
Trouble seeing output from the Raspberry Pi 4 on your monitor? The Pi 4 has two HDMI outputs. Specifically, these are micro-HDMI ports labeled HDMI0 and HDMI1.
Most problems with a Raspberry Pi 4 seemingly not booting are due to the HDMI cable being connected to the wrong port. Be sure to use the left-hand connector, HDMI0. You can use both ports if you are connecting two displays.
3. Raspberry Pi Not Booting? Check the Red and Green LEDs
When a Raspberry Pi boots (models 1 through 4), one or more LEDs will activate. One is red, indicating power (PWR); the other is green, indicating activity (ACT). (There is also a trio of Raspberry Pi LED lights on older models indicating the Ethernet status if connected.)
Generally, the red and green LEDs are key to troubleshooting your Raspberry Pi device. Green (ACT) flashes during SD card activity, and the red (PWR) LED blinks when power drops below 4.65V (the required voltage). To troubleshoot your Raspberry Pi model, watch out for the following:
- Normal operating status, when both PWR and ACT LEDs are activated
- Green LED off, indicating a problem with the SD card itself or the operating system installed on it
- Red LED blinking or off, indicating a problem with the power supply
The green (ACT) LED on models 1 to 3B+ blinks irregularly to indicate that the Raspberry Pi is booting up. However, it can blink in a more regulated manner to indicate a problem:
- 3 flashes: start.elf not found
- 4 flashes: start.elf cannot launch, so it’s probably corrupted. Alternatively, the card is not correctly inserted, or card slot is not working.
- 7 flashes: kernel.img not found
- 8 flashes: SDRAM not recognized. In this case, your SDRAM is probably damaged, or the bootcode.bin or start.elf is unreadable.
If any of these indicators occur, try a fresh SD card with a newly installed Raspberry Pi operating system. No joy? Keep reading for an alternative fix.
4. Raspberry Pi Not Turning On? Check the PSU
As noted above, power issues can cause a Raspberry Pi to fail. It might switch off or hang when running, or it might simply fail to boot at all. To read the SD card accurately, a stable power supply unit (PSU) is required.
To ensure your PSU is good enough, check that it meets the specifications of your Raspberry Pi model. Similarly, confirm that the micro-USB or USB-C cable from the PSU to the Pi is up to scratch.
A lot of people use smartphone chargers to power their Raspberry Pis. This isn’t usually the best idea; a dedicated, suitable PSU is preferred.
The Raspberry Pi has a resettable polyfuse to protect the device from overcurrent. While the polyfuse can reset itself, it can take a while, sometimes hours. If you have accidentally blown the polyfuse, you’ll only find out when you try booting later.
While you wait, shop around for a new PSU; the official Raspberry Pi power adapter is your best option. This 15W power supply is suitable for the Raspberry Pi 4 but provides the minimum power requirements for the newer Raspberry Pi 5. You’re better off picking up the 27W USB-C PSU for the Raspberry Pi 5.
5. Is the Raspberry Pi’s Operating System Installed?
Your Raspberry Pi will not boot if there is no operating system. You can install a Raspberry Pi OS on a microSD card or run a boot script to install an OS. Until an operating system is installed, the Raspberry Pi is essentially a glorified LED.
If you have installed the Raspberry Pi’s operating system onto an SSD (or other device), ensure it is functional and is correctly attached.
6. Check the microSD Card if the Raspberry Pi Doesn’t Boot
A working Raspberry Pi relies on a good-quality SD card for booting and running the OS. If the SD card isn’t working, your Raspberry Pi will be erratic or fail to boot.
You can troubleshoot the SD card by powering down the Pi and inserting the card into your PC. Use a reliable flash drive formatting tool and attempt to reformat (on Windows and Mac, use the SDFormatter tool from the SD Association). If formatting fails, the card is corrupt (SD cards from SanDisk can be returned under warranty).
When setting up a new Raspberry Pi OS, always format the SD card before writing the image using a reliable card reader/writer. Look for media with a high write speed and superior error checking to ensure a fast, efficient Raspberry Pi. Only buy SD cards from reputable suppliers, such as this Sandisk 64GB microSD Card on Amazon. As of 2024, the Raspberry Pi company sells an official Raspberry Pi microSD card that works especially well with the Raspberry Pi 5.
7. No Video Output on Your Raspberry Pi?
Your Raspberry Pi cannot display any video without a bootable SD card present and a working HDMI cable.
The display device must be capable of detecting the signal from the Raspberry Pi. If the Pi appears to be failing to boot because nothing appears on the screen, you’ll need to force HDMI detection.
Because the Raspberry Pi doesn’t have a BIOS, it relies instead on configuration files on the SD card. You can force HDMI detection by inserting the SD card in your desktop computer or laptop and browsing to the /boot/ partition. Open the config.txt file, and add the following at the end:
hdmi_force_hotplug=1
Save and exit the file, safely remove the SD card, return it to your Raspberry Pi, and then power up again.
Other video options are also possible. Old Raspberry Pi boards used TRRS for video and stereo audio. This means that you need a suitable TRRS A/V cable that can translate the RCA (red and white connectors) and composite (yellow connector) signals. This should work for you if HDMI is not an option.
8. Raspberry Pi Not Booting? How to Tell If It’s Dead or Defective
If you’ve got this far and the Raspberry Pi is still not booting, there is a chance the device is defective. It looks like you’ve been unlucky—Raspberry Pis are all tested following manufacturing.
Own an early Raspberry Pi (B, B+, 2B, or 3B—what are the differences between Raspberry Pi boards?)? One way to check if it is broken is to compare it with an identical model you know is working.
From the suspect device, remove the SD card, Ethernet cable, power lead, and HDMI cable. Remove anything connected, and substitute the working device with the same cables, peripherals, and SD card.
If this device boots, your other Pi is faulty; if not, then your cables, power supply, or microSD card are causing the problem. See above.
Meanwhile, there is a different way to check suspect devices for Raspberry Pi A, A+, and Zero devices. Remove all cables and the SD card, and connect the device via USB cable to your Windows PC. (Use USB-A to USB-A for the Raspberry Pi A and A+, micro-USB to USB-A for the Pi Zero models).
If working, the device will be detected, and an alert will sound from your PC. You’ll find the Raspberry Pi listed in Device Manager as “BCM2708 Boot”. On Linux and Mac, a working Raspberry Pi A or Zero will be listed in response to the dmesg command. You can follow a similar process for troubleshooting the Raspberry Pi Pico series.
Raspberry Pis purchased from official resellers have a 12-month warranty, but don’t return it without first checking the terms and conditions. Managed to get everything up and running? It’s time to think about a Raspberry Pi project. ​