You have a Raspberry Pi, everyone is connected, ready to go… but when you plug in the power, nothing happens. Something, somewhere is wrong, but what? And what can you do about it?

Here are five things to check if you need to troubleshoot a Raspberry Pi that should work but won’t boot for some reason.

1. Make sure it’s not a download, check the LEDs

When the Raspberry Pi boots up, one or more LEDs will turn on. One red, indicating power (PWR); the other is green and indicates activity (ACT). (There are also three LEDs showing Ethernet status, if connected.)

Raspberry Pi Model B

So what do these LEDs mean? Well, there is a normal condition where both PWR and ACT lights are on. ACT will flash when the SD card is active, and PWR will flash when the power drops below 4.65V. Thus, if the red PWR LED does not light up, there is no power.

If only the red PWR LED is active and there is no blinking light, then the Pi is receiving power, but there is no readable boot instruction on the SD card (if present). On the Raspberry Pi 2, the ACT and PWR LEDs are lit, which means the same thing.

When booting from an SD card, the ACT light should blink irregularly. However, it may flash in a more controlled manner to indicate a problem:

  • 3 flashes: start.elf not found
  • 4 flashes: start.elf cannot start, so it may be corrupted. In addition, the card is not inserted correctly or the card slot is not working.
  • 7 flashes: kernel.img not found
  • 8 flashes: SDRAM not recognized. In this case, your SDRAM is probably corrupted or the bootcode.bin orstart.elf file cannot be read.

If any of these indicators occur, try a new SD card with a freshly installed Raspberry Pi operating system No joy? Scroll down to see what the problem might be.

2. Is the power adapter good enough?

As noted above, power issues can cause your Raspberry Pi to crash. It may shut down or freeze while running, or it may not boot at all. This is because a stable power supply unit (PSU) is needed to reliably read an SD card.

To make sure your power supply is good enough, make sure it matches the specification for your specific Raspberry Pi model. Similarly, make sure the micro USB from the power supply to the Pi is down to zero. Many people use smartphone chargers to power their Raspberry Pis. This is usually not the best idea; a dedicated, suitable power supply is the preferred approach.

The Raspberry Pi has a resettable fuse. This polyfusus may clear itself, but it may take up to a few days. If you accidentally start polyfuse, you will only know about it the next time you try to boot. It’s worth taking the time to buy a suitable Raspberry Pi power supply, such as the CanaKit 5V 2.5A adapter at Amazon.

3. Is the operating system installed?

Your Raspberry Pi will not boot if there is no operating system installed and it lacks a boot script that allows you to install the OS (like NOOBS or BerryBoot.).

So, if there is no OS installed on the SD card, you will not enjoy the Raspberry Pi. Do this by making the OS available. Install Raspbian (or Raspbian Lite if you’re short on time) or use NOOBS to start your Pi and select an OS to download and install.

4. Make sure the MicroSD Card is working

A working Raspberry Pi will rely on a good quality SD card to boot and is usually running an OS (although later models may subsequently boot from USB devices). If the SD card is not working then your Raspberry Pi will be unstable or simply won’t be able to boot.

SD cards must be formatted before use.

Let’s start by checking the health of the card. You can do this by turning off your Pi and inserting an SD card into your computer. Use a trusted flash drive formatter and try reformatting (on Windows and Mac, use the SDFormatter tool from the SD Association). If the format fails, the card is damaged (SD cards from SanDisk can be returned under warranty).

When setting up a new Raspberry Pi OS, it’s always best to format the SD card before burning the image. This means using a reliable card reader/writer as well as suitable media. Look for media with high write speeds and excellent error checking to keep your Raspberry Pi fast and efficient.

Only buy SD cards from reputable vendors such as the Sandisk 64GB microSD card on Amazon. Other notable brands include Samsung and PNY, both of which can also be found on Amazon.

5. No video output?

Your Raspberry Pi cannot display video without an SD card. There is no onboard BIOS, so nothing can be displayed. Therefore, you need to make sure you are using a reliable working HDMI cable.

Meanwhile, the Pi itself must detect the display. Similarly, the display device must be able to detect the signal from the Raspberry Pi. If the Pi won’t boot up due to nothing appearing on the screen, you need to activate the HDMI detection feature.

You can do this on your computer by inserting an SD card and navigating to the /boot/ partition. open config.txt file and add the following to the end:

hdmi_force_hotplug=1 

Save and exit the file, safely remove the SD card, return it to your Raspberry Pi, and try powering it up again.

Meanwhile, if you are using NOOBS to install the operating system on your Raspberry Pi and nothing appears on the display, you can try some keyboard shortcuts. During the first ten seconds of boot up, pressing 1, 2, 3, and 4 on the keyboard will cause the display output to switch between HDMI perfect, HDMI safe, PAL composite, and NTSC composite.

Other video options are also possible. However, the latest Pis use TRRS, which means you need the right cable that can carry RCA (red and white connectors) and composite (yellow connector) signals.

You can find a suitable TRRS audio/video cable on Amazon. This should work for you if HDMI is not an option.

How to Identify a Dead or Defective Raspberry Pi

If you are far from successful, chances are your Raspberry Pi is faulty. The chances of this happening are slim as they are all tested after manufacture.

Raspberry pi zero

For a Raspberry Pi B, B+, 2B, 3B, or 3B+ (What’s the difference between Raspberry Pi boards?), the only way to figure out if it’s broken is to have an identical model in your hands, one you know works. From the suspicious device, disconnect the SD card, Ethernet cable, power cable, and HDMI cable — and everything else that is connected — and replace the working device with the same cables, peripherals, and SD card.

If the device boots, your other Pi is faulty; if not, the cables, power supply, or SD card are causing the problem. See above.

Meanwhile, for Raspberry Pi A, A+, and Zero devices, there is another way to check for suspicious devices. Disconnect all cables and the SD card and connect the device via a USB cable to a Windows PC (USB-A to USB-A for Raspberry Pi A and A+, micro-USB to USB-A for Pi Zero models).

If it works, the device will be detected and an alert will sound and you will find the Raspberry Pi listed in Device Manager as «Loading BCM2708». On Linux and Mac, you will find a running Raspberry Pi A or Zero listed in response to the command dmesg in the terminal.

The Raspberry Pis comes with a 12 month warranty, but don’t return it without checking the conditions first.

Raspberry Pi Boot Issues: Fixed!

So, here are five things to check to fix your Raspberry Pi boot issues. Here is the summary:

  1. Check the LEDs
  2. Is the power adapter suitable?
  3. Have you installed an operating system?
  4. Is the microSD card reliable?
  5. HDMI output disabled?

Meanwhile, if your Raspberry Pi is one of the few that is truly faulty, use the steps above to confirm it. And if you’re ready to try something different, check out competitions like NanoPi NEO4

Were you able to get everything up and running? Big! Now take a look at these amazing Raspberry Pi projects to get you started.

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