No, this time your the annoying idiot.
It's a pawn shop, not your local camera store. They do not need to demonstrate how the camera works for you. Nor do they need to play music so you can see if you like the speakers they sell. Or provide a cable hookup so you can test out that tv in the corner.
They could care less if you buy it because someone else will, without fussing a moment about seeing it working. How much money are they supposed to waste making everything testable for the few people like you that piss us all off by not being capable of just accepting it's cheap and getting it.