Can anyone help me? My car was acting possessed (interior lights blinking, doors locking and unlocking by themselves) then my keyless entry stopped working.

I tried unplugging the battery cable for 20 minutes and plugging back in. Still doesn't work.

Can anyone give me any pointers on what to check or try? I don't really want to take it in so they can charge me an arm and a leg!

Thanks!
Melanie