Originally posted by hangman43 ........ shows full but once you prees shutter it comes up battery depleted. Any ideas what it could be? One of the batteries is a Pentax the other is a no name.
This could - I don't say it is - be a shortcut somewhere in the electric circuit. As long as the camera is passive all is fine (as far as the volt meter is concerned), but when you press the shutter, you get an excessive load on the battery and the voltage drops instantaneously. I have experienced that once with a built-in flash that was malfunctioning.
Have you tried with a different lens? Have you tried with a reset? Have you tried with an external power supply?
If so and without any luck, I think you should send your camera in for repair right away.