Troubleshooting a friend's Sony SONY KDF-60WF655.

Issue:

Turn the TV on and it is fine for about 20 seconds (picture, etc.)

After 20 seconds, the TV "turns off" (no picture) and after about 1 minute, "turns on" and repeats the process.. has picture, shuts down after 20 seconds.

We let it go for about 30 mins this way.

Any advice or pointing in the right direction is greatly appreciated.

Thanks!