820-3437 white screen no boot sometimes

[No-Clean]

Board came in with some corrosion near the side of the SMC, first I reballed the SMC then I eventually replaced the SMC, board worked for a bit then after that it now starts loads the OS and at the end of the bar it just hands there and doesnt finish loading the OS, I tried different BIOS and board no longer starts and fan starts on and off indefinitely instead of the 3 times is supposed to, BIOS came from here: https://boards.rossmanngroup.com/threads/820-3437-wont-boot.50107/

This board has trolled me for a bit now.

 

[2informaticos]

Maybe corrosion affected PCH/CPU areas too.
You can try heating with quality flux.
Also check all SPI Bus Termination resistors adn traces.

The board doesn't start now even with first BIOS?
Did you try SMC bypass?

 

[No-Clean]

Ok replaced U8000 and heated board for a while to make sure all UC cleaner was gone and now board boots every time.

Thanks!