The output above from DiagROM has the same symptoms of a memory address error. I'd suggest using the new DiagROM v1.3 which now has the ability to test for and report address errors:
https://www.diagrom.com/index.php/download/The common problems that can cause memory address errors on the A2000 are either typically one or more bad DRAMs, or bad/intermittent contacts in the PLCC84 (Agnus) IC socket. I've seen plenty of socket defects despite the socket appearing to be OK, so if in doubt, replace it.
