Oh that is one of those boards. I assumed the diodes you changed on the bottom? From my experience doing over 70 SE30 reloaded boards, sockets for plcc suck. Many times, the chip legs are very bad and do not make contact in the socket. I have tried sockets and many times, I end up removing them and doing direct solder. To me it sounds like you are having a memory issue in the first few K of memory. A few people have send me their Colin boards to fix and most of the time, it was one of the diodes either not soldered well or one was not replaced. Another item to check is if all the birdseed on the bottom is there. Look to see if any items were knocked off by accident. It happens. Should you give up, last resort, I’ll look it over if you wish just cover shipping.