Sega CD Model 1 problem (not the fuse or tray.)

The unit seems dead. I swapped boards between 2 units and narrowed it down to the motherboard, the sound/power board has a blown fuse but is otherwise good as it worked fine with a bypass in another unit. The drive also works fine. The unit when plugged in does one of the following at random:
1: Ready and Access lights off
2: Ready light on, and Access light off
3: Ready and Access lights on
4: Ready light dim and Access light dim (happened with the SCD unplugged due to leakage from the genesis)
5:Genesis Power light dim (happened with the Genesis on but unplugged)

Anyone know how the Sega Genesis starts the Sega CD? Also this unit has an Eprom bios, could bitrot be part of the problem?

Edit:it seems pins 105-109 on IC2 are lifted, Ironically I fixed that on my own unit several years ago and the slight difference in the symptoms could be due to more affected pins.