Well,
If you're sure the simms you used are good, then it can be : ramsey, agnus - sorry alice ;-) - or some of the 74245 in the memory area, how is the battery looking? has it leaked on the mobo?
Be sure that ramsey is well seated and in the right position, try to replace it, look at the solders on alice, try to boot with both mouse button pressed right from power on, tell me what happens.
remove all fast ram, let the chip simm only, for testing you don't need more.
If you get green screen ever, then alice or the 74245 must be replaced, if it's a battery damage, the mobo needs to be reconstructed. Ask a repair shop near you or Amiga.fr.
