Vestel 50" Edge lit 17ips20 lights for 15 seconds

[clark97]

Just acquired a luxor 50" Edge lit model lux0150003
17ips20 and 17mb95
Powers up and stays on for around 15 seconds before losing backlight. If switched off and on comes back up for around 8 seconds before losing back light.

Just wondered if anyone had seen this before, I'm drawn to u500 though could be leds. Will start with psu before opening the screen to check leds.

Thanks in advance for any help.

Clark