Sorry, can't help with fuse location but the slides are typically direct-wired to the battery. Possibly chassis battery rather than house, but I think in '03 they were usually on the house battery.
Also, find the slide controller (the switch simply triggers the controller to close the power circuit, in or out) and see if you have power there. Could be a bad switch or a failed controller. Rack & pinion gear slides have limit switches that open the circuit to stop movement - one of those could be stuck open from when you closed the slide last.