Hitachi 42hds69 failure to power ON

[voltron]

HI all, After 3 years of successful live of my hitachi 42hds69 here come the problem. Occasionally, the TV set does not power on, neither the remote works not the power button on the front panel. Any ideas if it is a power supply unit problem or problem on the main board... Please advise with any suggestions of how to identify the problem myself. Any help is appreciated...thnks