The unit keeps switching off as soon as it is switched on?

My friend has a Panasonic DVD/VCR combo, and a compatible Panasonic TV. The TV works fine, but yesterday, when in rewind mode, the VCR froze. We cannot now control the VCR- either by use of remote control or controls on the unit - nor can we remove the cassette that is still in the machine. Incidentally, the child lock device has not been activated.