I have a LG Home theater set...which wont switch on.

1. When I on the main power ..a red LED light come on.

2. When I press on the power on button, the red LED turns green
briefly for 1 sec and switch back to red.
The whole unit just switch on briefly for 1 sec.

3. When I off the mains the red light stays on for almost 5 sec which
show a good capacitor.

I have check the transistor for bistable circuit and they seems OK.
Any other ideas?