Lord Buckingham won't start

My 03 Buick LeSabre, Lord Buckingham, won’t start. Battery’s good, it won’t jump, and I tried the other key. Also the driver’s side seat won’t heat, and it keeps insisting that the gas cap, also on the driver’s side, isn’t on right. Could this be fuse or short related?

The gas cap issue could be a vented gas cap. After tightening it down turn it back counter clockwise until it stops without releasing the cap. See what happens.