Serious electrical problems??
 

Hi, everyone. New to this forum. Just bought my first Cadillac. 2003 Deville. It is supposed to be a temporary car, as it has a lot of minor problems (blower motor is shot, needs general TLC, lots of cosmetic damage.) It also has one serious problem and that is that TWICE now, the car does not start. No noise whatsoever when I turn the key in the ignition. At this time, nothing on the car works. No lights, trunk won't pop, seats won't move, etc.
I checked the battery terminals and did not see any corrosion. It has a brand new battery.
When I lifted the seat to look at the battery, the lights, etc came back on and the car started. As soon as I put the seat back down, there is once again no power. As if something is shorting out.
Anyone have any suggestions as to what the problem could be? Thanks in advance.

Suggest checking tightness of every connection. If this doesn't fix it check continuity of all wires.