|There is no battery on the video card.|
You must be referring to the cmos battery. Doing so would require you reconfiguring the bios's time and other settings. You don't mention doing that.
Usually you can not move new ram to older machines.
Was that blank screen with a blinking cursor in the upper left corner? That is an indication the master boot record is missing.
Your bios screen with missing letters I have seen before and it was a faulty video card in my case.
Sounds like working in the guts of the computer may have made things worse.