Welcome to Amiga.org.
Your A4000 doesn't boot, right? With a green screen? That's failure of Chip RAM. If it boots - then it's finding some Chip RAM. What exactly are the symptoms? Have you tried a different RAM chip? Try any 72-pin SIMM as even a 1MB one will work, and higher capacity ones will usually work too (albeit usually with 1MB instead of 2MB).
Is there any battery damage to the motherboard?
