SimonK

I have had a my VR3 switch off at depth a couple of times.

When I got the VR3 it was very difficult to get the battery cap off, tool was no use and I ended up using pliers. The threads had been distorted, it looked like the sort of bodge people were doing to Hammerhead battery caps to get the battery to work. I cleaned up the thread so that I could open and close the cap with the supplied tool.
On a couple of dives sometime later the unit switched off at depth (20m). I could reproduce this on the surface by pressing hard on the battery cap. My conclusion was that the cap was not screwed down to its stop so when pressure was applied the two halves of the cap screw thread separated breaking the circuit ( it is a very coarse and loose thread).
I have now cleaned up the threads as best I can and applied some lubrication to make sure the cap can be easily screwed in and out. I always ensure that the cap is screwed all the way in so that the plastic part of the cap is hard up against the computer body, this ensures that the cap does not move under pressure.

Since then no more problems, except that its a spectrum and eats batteries but that's another story.

Simon