99-00 Denali won't start

99-00 Denali has sat for 5 months while deployed. Can't get it to start. So far I have changed the battery, the fuses, and the fuse relays. We are talking no lights (dash or head or anything) no radio nuthin. No indication of power to the vehicle whatsoever. I would rather not tow it to the dealer if I can fix at home. Any ideas anyone?