Sounds like the DC to DC converter. If you are a technician, remove all power, pull the large cover off of the tape side of the camcorder, look near the rear of the camera and you will see a shiny metal box. See if it is loose. If so or even if not, unplug it and plug it back in. Sony did not build in a holder for this item and it could have shaken loose. Make sure it’s in it’s slot securely and repower the camera.
This has happened to me twice. I now have a rubber pad inside the cover which keeps light pressure on the converter.
There are also a dozen (14) boards on the switch side of the camera that could have come loose, but not likely.
If it’s a rental camera, call the emergency number that came with the unit.
Also, ALWAYS turn the power switch OFF before changing batteries or power connections. It has a built in buffer which prevents power surges.
Good luck
Steve Wargo