I got the source of the intermittent booting problem pinpointed to the EEPROM chip only making contact intermittently with the PCB, but getting to that conclusion was an absolute pain. I want to document it here for posterity.
TLDR: RPi4 was booting intermittently. Suspected EEPROM issue. Applying pressure on EEPROM chip by A/V jack before power on the board resolved booting issue.
The issue: I got a bunch of used RPi 4s, and this one happened to boot intermittently. Power LED would light up, and Activity LED would flash on precisely once before nothing else happened even with nothing plugged into the board. About 1 out of every 20 power on attempts would result in a successful boot. Once booted, the board would be stable and able to reboot just fine.
Things I tried but didn't work/couldn't help me identify the problem:
_Swapped power supplies, all non-official.
_Swapped power cables, all non-official again.
_Swapped microSD cards.
_Viewed both sides of the board with a thermal camera. Didn't see any short.
_Inspected the board under microscope for damage SMD component. Didn't see any.
_Inspected the inside of the USB C connector. Didn't see any damage.
_Inspected the microSD card slot. Didn't see any damage.
_Checked 5V and 3.3V rails. Both were present and within specifications.
_Updated bootloader using both RPi Imager/microSD card and rpi-eeprom-update methods (once the board booted).
RPi Imager/microSD card method would consistently fail, but rpi-eeprom-update managed to successfully update the bootloader.
The solution: after reading the documentation on the boot sequence for RPi 4 and a bunch of other posts with similar problems, I suspected for some reasons the bootloader wasn't loaded even when the board was powered sometimes. The -single- EEPROM chip by A/V jack (board revision 1.4) couldn't be entirely dead since the board could still boot sometimes. I used a pen to apply pressure to the EEPROM chip before powering on the board, and the board booted 100% of the time now.
Given the location of the chip, I'm going to add a bit of flux to it and then heat it up with hot air soldering gun to attempt to melt the broken solder joints there.
TLDR: RPi4 was booting intermittently. Suspected EEPROM issue. Applying pressure on EEPROM chip by A/V jack before power on the board resolved booting issue.
The issue: I got a bunch of used RPi 4s, and this one happened to boot intermittently. Power LED would light up, and Activity LED would flash on precisely once before nothing else happened even with nothing plugged into the board. About 1 out of every 20 power on attempts would result in a successful boot. Once booted, the board would be stable and able to reboot just fine.
Things I tried but didn't work/couldn't help me identify the problem:
_Swapped power supplies, all non-official.
_Swapped power cables, all non-official again.
_Swapped microSD cards.
_Viewed both sides of the board with a thermal camera. Didn't see any short.
_Inspected the board under microscope for damage SMD component. Didn't see any.
_Inspected the inside of the USB C connector. Didn't see any damage.
_Inspected the microSD card slot. Didn't see any damage.
_Checked 5V and 3.3V rails. Both were present and within specifications.
_Updated bootloader using both RPi Imager/microSD card and rpi-eeprom-update methods (once the board booted).
RPi Imager/microSD card method would consistently fail, but rpi-eeprom-update managed to successfully update the bootloader.
The solution: after reading the documentation on the boot sequence for RPi 4 and a bunch of other posts with similar problems, I suspected for some reasons the bootloader wasn't loaded even when the board was powered sometimes. The -single- EEPROM chip by A/V jack (board revision 1.4) couldn't be entirely dead since the board could still boot sometimes. I used a pen to apply pressure to the EEPROM chip before powering on the board, and the board booted 100% of the time now.
Given the location of the chip, I'm going to add a bit of flux to it and then heat it up with hot air soldering gun to attempt to melt the broken solder joints there.
Statistics: Posted by brokenpies — Thu Mar 06, 2025 6:33 am