Connect the jump pack to the jump start terminals in the engine bay. Try operating the driver's side power seat - either the recline or the for - aft. If the driver's side power seat doesn't work then I think your jump pack is dead. There are two fuses between the jump start terminals in the engine compartment and the power seat. One is the main big ass 120 amp fuse and the others are 20 amp so very little to go wrong. Check the #9 120 amp fuse; however, rare for that to pop without you knowing that something had happened. Also, that fuse will not prevent the headlights from operating since they are not supplied through that fuse.
If the driver's side power seat works with the jump pack connected to the jump start terminal in the engine bay, move the jump pack and connect it to the battery terminals. Try the seat test again. If the seat does not move then there is a problem with one of the following:
- the battery post terminals
- the battery cable ground connection to the body
- the positive cables from the battery