Bad CMOS battery wouldn't prevent it from booting. That would only prevent BIOS settings from being saved.
If you're getting bad RAM codes, then I'd send in your RAM for warranty (depending on the brand, it's usually lifetime warranty). Could take it to a computer shop and see if they'll test it for you since you don't have a booting system (if it could at least boot up, I'd suggest just running Memtes86+ yourself).
Edit: ninja'd by MidnightShadow