Electrical problem. No power.

I have a 2000 Century that has sat for a few months. I jump started it and it started up fine. I threw it in drive and started turning the wheel when it died. It also lost electrical everywhere in the car. no dome light, no dash lights, no ignition, as far as I can tell no nothin. I have checked all the fuses and swapped the relays I could. What else could be the problem?

Nevermind, I got it going. I think maybe it just died for whatever reason and when I tried to jump it again I had a bad connection on the jumper cable. At least I'm hoping that was it.