Sorry to hear about your problem, I will be happy to help. I hope you find the time and information I provide to be valuable and will honor the good faith system of this site. Please be aware the answer to your question may not be good news and the procedures that are required to solve your problem may be complex and could involve replacing parts that can be expensive.
Solving your problem depends a lot on your ability to follow directions very carefully, be patient, and continue the communication process with detailed responses. The more information you provide the better chance of solving your problem.
Get the shutdown error code- After the Tv tries to turn on and shuts down do not reset or unplug, go up to the front panel, press and hold MENU + DEVICE (INPUT) until you see a light on the front start to blink a two digit code like 3 blinks pause 4 blinks repeat, or 5 blinks pause 6 blinks repeat, or 6 blinks pause 6 blinks repeat, etc. What error code did you get?
Inspect the lamp- Has the lamp ever been replaced, when? Find the trap door where the lamp goes, unplug the Tv, take the lamp out and look down inside the glass part. Is it clear and in tact or is it dingy, cracked, bulging, shattered, etc?