Hi have a 42" LG TV model. When I go to turn it on the power light flashes red but then doesn't turn on. Took the back off and got rid of all the dust in there. Looked at it from the back whilst trying to turn it on and the back lift comes on for 2 seconds then it's dimming. I've tried unplugging it for half hour still doesn't help. Please someone help me its driving me mad!