Try re-seating the lamp. With the TV unplugged, open the lamp housing door, unscrew the lamp, pull it out, push it back in, screw it back in securely, and fasten the lamp door. Try powering it on again to see if that helps.

If re-seating the lamp doesn't fix the issue (You might try once or twice), then the unit may have received damage from a power surge and would need to be serviced.