I've acquired another "faulty" ThinkPad!
Seller describd as faulty but "boots to BIOS". When I unpacked I noticed there were a load of screws missing - always a bad start

Anyway, initial propblem seems to have been with the RAM module as it would not boot at all except with a 1-3-3-1 beep code. Once the module was removed it would start to boot, but now stops with a "0175: Bad CRC1, stop POST task" error. I've changed the CMOS battery for a known good one, but the problem persists. Pressing F1 (as prompted) causes the system to hang.
An IBM diagnostic document suggests "The EEPROM checksum is not correct (block #6). Have the computer serviced." is the fix. Would this happen if there had been a failed BIOS flash/update? Other than a faulty BIOS or motherboard, are there any other likely explanations?
TIA