I’ve purchased a used Mamiya 7II on eBay. Despite using a fresh battery, there are no lights showing in the viewfinder when I run the battery check (page 9 of the manual). Nor am I able to release the shutter per the camera function test (page 14.) Although a red warning light is supposed to appear if the shutter isn’t tripped, that doesn’t happen. The lens is mounted properly and the dark slide is in the open position. I'm assuming the viewfinder should display a light even without film in the camera. Am I doing something wrong or should I return the camera? Thanks in advance for any help the readers of this forum might provide.