Saturn Repair: 1998 SC2 electronics flipping out, gm store, electronic control unit

Question
My mother owns a '98 Saturn SC2 that, until now, has been rock solid.  Apparently, after having left the car sit for 4 days without driving it and possibly having drained the battery by leaving her XM reciever plugged in, odd things have been happening.  At the top of the list is that her electronic trunk latch keeps releasing itself without reason at any given time.  According to her (she lives in California, me in Indiana, so I can't look at anything myself), she had the battery checked by someone this past Friday.  They said it was fully charged.  She drove it home Friday afternoon, it sat all day Saturday, and Sunday it wouldn't start... only click-click-click when she turned the key.  The headlights don't dim completely if they're on when she tries to start it, which I would expect to happen if the battery were shot.  All of the indicator lights on the dash "go crazy" when she tries to start it.

Aside from the 4-day "left it sitting", she can't recall anything that might have happened as a turning point between peachy and freaky.

The local GM store won't touch it and the closest Saturn dealership is 90 minutes from her house.  Not having much experience with Saturns, I don't know what to tell her to look for... fusible link?  Bad battery cables?  Bad starter draining the battery?  Bad alternator draining the battery?  Fried electronic control unit?  Ever seen a trunk pop itself randomly?  

Thanks in advance,
Nate  

Answer
Nate,
 I would check the battery terminals.  They can become corroded or disloged.  Poor contact at the terminals is one of the only reasons that an S-Series will "wig out".  The battery can still show a full charge (voltage wise), but when a large load (amperage) is placed on it, like starting, the terminals don't have enough contact to conduct the aperage required, hence your situation.  I would probably check that out first...let me know how it comes out.

Chris