Hello, and sorry you're having problems. We are now connected on this website- which saves you money over having a Tech come to your home, and in many cases we can fix the problem you're having. In other cases, these things do require additional parts to fix. But I can help you with that as well.
Offhand, whenever these sets shut themselves off after power ON, it indicates a hardware failure in the TV causing this problem. It's not within normal operation, or a setting issue that causes it to cycle itself back off. It's a protection mode preventing further damage, or fire in the TV due to a short circuit.
Most commonly the High Voltage circuit, the Convergence circuit, or the power supply PCB itself has a hardware fault (failed regulator, capacitors, shorted transformer, etc.). To narrow it down requires testing inside of the TV with a service manual, a multi-meter AND (most importantly) experience working with high voltages on a PCB level and skill testing down to a component level. There are lethal voltages inside of these sets (1,000's of volts) that can KILL you even after the TV is unplugged.
So in most cases this is going to require someone that's skilled with this type of repair, and the average cost is between $250-$400 parts and labor (depending on the fault).
However it's worth it to try a hard reset, as sometimes the processor in the TV can simply have locked up.
The first thing you would try, is disconnect the set from power, then press and hold the power button on the TV itself (not the remote), for 10 seconds and release. Then plug the set back in, and also check that the power cord is connected tight at the TV as well. Press power once, and see if the set powers up normally. Try this procedure up to 3 times, and please let me know what happens.
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