I know there are two seperate relays for the power seats, and that one handles half of the functions of each seat. But there should be a fuse that powers up the relays. Later cars have a convenience relay, so carefully inspect all of the fuses for small hairline cracks and spin the fuses in their holder to ensure proper contact.
Last thought: They are powered two ways, one with either front door open, and second with the key in position 1 or 2 (acc and run). Check both ways.....