Mine's in the storage shed, where I keep it, for aiming dishes lol. Here's the note from the manual about factory defaulting the 3500:
Select Tools from main menu, scroll down to Default Value,, it will ask for password (0000), enter that, it will erase all the unused transponders that are clogging up your memory. And everything else you have stored, so you will have to rescan all sats once you do this.The rec will be as it came new from dealer.