Hi! I'm working on 820-00138 which is not booting to OS. Actually for most of the time it's stuck on Apple logo, there is even no progress bar. Sometimes after many SMC resets it will load OS to user screen or opens boot drive selection, but for most of the time there is only Apple logo. Board has no signs of liquid or other damages. I suspect bad BIOS, could you please share clean one for this board? Or at least clean ME in mine (link below)?
A1398_820-00138_BACKUP.bin
drive.google.com