Here's a thought - with power removed, remove the two screws on the front of the VFD - not the ones mounting this to the back plate, but there's a removable panel on the front of the VFD - lower half. remove those and the panel slides off - exposing the screw terminals. Get a photo of that.

EDIT: I'm clutching at straws of what you can examine safely at this point. It'd be embarrassing if one of the terminals had come loose from there.