OBERHEIM SYNTH

Hey all, first of all- hi
I was running out of options until I found this wonderful group!

Secondly,
I just purchased an oberheim drummer off ebay and it started giving me problems immediately. The issue is that, if I let it sit and rest for a bit, it starts up fine and works great, until after about 1-3 minutes when all of the function become inaccessible. AKA it shows "0" for preset, and it is unchangeable, as well as all other functions show "oF" and I cannot change it. This will happen immediately if I just switch it from on to off.

I have it opened up here (got scared that I had destroyed it on one or two occasions while playing with the ram and eprom). I am trying a new battery but i don't have my soldering iron here at school so it is just sitting between the tabs.

what does the battery do btw?

And I have a new 32K X 8 ram on its way. 

Any other suggestions?

Thank you!