My build won’t boot: a step-by-step fix list

You wrote the build, plugged in, and… nothing. Or a rainbow square. Or an error you have never seen. Deep breath. Work through these in order, because nine times out of ten it is one of the first four.

1. Give it time

The first boot of a big build can sit on a black or logo screen for 10 minutes or more while it sets up. Leave it 15 minutes before deciding it has failed, and do not pull the power while it works. See first boot.

2. Check the boring stuff

• Card or drive pushed fully in.
• TV on the right input. Try another HDMI cable if you have one.
• Raspberry Pi 4 or 5: use the micro HDMI port nearest the power socket. The other port often shows nothing.
• Unplug extras (USB hubs, extra drives) and try with just the pad.

If the device is clearly running but the screen is blank, see black screen or no sound.

3. Check the power

Weak power causes boot loops, rainbow screens and the lightning bolt icon. On a Pi, use the official supply: 5V 3A for a Pi 4, 5V 5A for a Pi 5. Phone chargers often are not enough. See Raspberry Pi basics.

4. Right build for the right device

A Pi 4 build will not boot a Pi 5, a Pi image will not boot a PC, and so on. Re-read the build’s post and check it names your exact device.

5. “start4.elf is not compatible”

If you see “start4.elf is not compatible. This board requires newer software”, your Pi’s firmware (its built-in start-up code) is older than the build expects. It takes a few minutes to fix: write Raspberry Pi OS to a spare card with Raspberry Pi Imager, boot it once so it updates the firmware, shut down, then put your build card back in. Full steps on our start4.elf is not compatible page.

6. Re-write the image

A write can fail quietly, especially if the card was pulled out early. Re-write it, and if your tool offers to verify after writing, let it. Full steps:

• Writing an SD card
• Writing an SSD or hard drive
• Writing a USB stick

Also check you wrote the .img file itself, not the .rar archive, and that the image fitted (see image will not fit).

7. Suspect the card or drive

Cards wear out, and fake cards are everywhere. If a re-write fails or the build boots once then dies:

1. Try a different card or drive, ideally a known good brand.
2. Test the suspect one with H2testw. See buying SD cards.

8. Suspect the download

A damaged download writes a damaged image. If extraction showed CRC or checksum errors, the archive is faulty. See extraction errors and grab the files again, ideally by NZB: see download failed.

PC builds that will not boot

• Pick the drive in the boot menu. At power on tap F12 (or F8, F11, Esc or Del, depending on your PC) and choose the build drive.
• Secure Boot in the PC’s BIOS/UEFI settings can block some Linux-based builds like Batocera. Turning it off is a common fix; check the build’s post.
• Windows folder builds do not boot at all: you run them from Windows. See installing PC folder builds.

Steam Deck

Hold Volume Down and press Power to open the Boot Manager, then choose the SD card. See Steam Deck builds.

Still stuck? Leave a comment on the build’s post with your device, power supply, card or drive, and exactly what you see on screen. You can also ask in our Discord.