LCD Powers on, powers off

Samsung LCD. 1.5 years old. Blank screen out of nowhere, now turns on, shuts off every few seconds (no picture) when plugged in.

Motherboard and power supply appear normal.

When Ribbon cable is disconnected from motherboard, the TV will stay on with blank screen, and can hear sound! Reconnect the ribbon, and TV goes back to turning on/off.

When ribbon cable remains attached to motherboard and is disconnected on other end from [LCD strip?... not sure what its called, runs along bottom of screen] tv stays on, blank screen, has sound. And when reconnected, again, turns on/off on its own.

Same results when lifting the ribbon latches on the part [lcd strip?] that runs across bottom of screen. Lifted - TV on, blank screen, sound. Clamped down - powers on/off on own.

Same result with a replacement motherboard.

Thoughts? LCD screen kaput outta nowhere?