issue with a fusible link (little box in front of the battery)? This of course assumes the seat power buttons are all working OK and not as posted above by MaxxAction.
Pulling the seat power connector and buzzing it out will tell you quickly if the buttons have an issue or not (ie, power live or not)? Might be able to run the same test by pulling off the seat button cover shroud and getting to the wires that way (been a while since I had it apart)...