Depending how many "months" its been unplugged, you could have an issue of the backup battery going dead (this provides a trickle of current lasting many months to a few years, preserving the recorders start-up data when its unplugged). Since the EH85 is a relatively recent model, its probably too soon for the battery to have exhausted, but you never know. The most likely cause is a blown fuse, as jjeff advised. A Panasonic with a good fuse but faulty power components usually turns on and displays an error message, or turns on but refuses to do anything. Completely dead would indicate checking the fuse before going further. Good luck!