I never found the key to the supply room, I think I checked all the boxes but after dying 15 times I just couldn't keep up playing.
I was worried that would happen on someone's playthrough. I did try to fix it by increasing the chances you would find the key exponentially, but that still left the very slim possibility that you could check literally every box and it would be the very last one you checked. I can fix this tho in an update.