Raspberry Pi 4/400 Flash Codes
If you're having trouble with your Raspberry Pi 4 or 400 not booting, usually the culprit is a bad power supply or problems with the SD card or image. If you've confirmed that the power supply is good and it's not even showing the usual power-on screen, check to see if the green LED is flashing - it could be giving you a hint as to what the problem is.
If a Pi fails to boot for some reason, or has to shut down, in many cases an LED will be flashed a specific number of times to indicate what happened. The LED will blink for a number of long flashes (0 or more), then short flashes, to indicate the exact status. In most cases, the pattern will repeat after a 2 second gap.
Long flashes Short flashes Status 0 3 Generic failure to boot 0 4 start*.elf not found 0 7 Kernel image not found 0 8 SDRAM failure 0 9 Insufficient SDRAM 0 10 In HALT state 2 1 Partition not FAT 2 2 Failed to read from partition 2 3 Extended partition not FAT 2 4 File signature/hash mismatch - Pi 4 4 4 Unsupported board type 4 5 Fatal firmware error 4 6 Power failure type A 4 7 Power failure type B
so:
- if the ACT LED blinks in a regular four blink pattern, it cannot find bootcode (start.elf)
- if the ACT LED blinks in an irregular pattern then booting has started.
- if the ACT LED doesn't blink, then the EEPROM code might be corrupted, try again without anything connected to make sure.
At least one of these flash codes (SDRAM failure) means your Pi has a hardware fault and you should get it exchanged if it's still under warranty.
Earlier Raspberry Pi models also have flash codes. Check out the Raspberry Pi forums for more information.
