I'm so sorry to hear that. I think i definitely want to make a patch where the required object is more clearly presented as something to pick up. I can totally let you know how to use the scanner in the meantime though.
Spoilers:
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Use the janitors code from the first instance of the freezer to enter the closet in the restaurant proper. Then grab the severed hand from the shelf. When using the scanner, select the option to use the severed hand.
Sorry for the delay in response, I am working on getting my other game out of early access right now, but I will soon return to add some improvements to The Training Video. Thanks so much for playing the game.