The power won't stay on for more than a few seconds and then shuts down

I can not acces my Facebook deos not recognize or mail or password,how I can restart t.v to install and to atarte again please help me , thank you

clearly sounds like fuel starvation, I would be looking at the throttle body, they need servicing every couple of years, they fill up with like grease and block tick over hole.....

It must be a problem with electric connection. you should check whether it is OK or not. If it is okay, read instruction manual.

Hold the power button in for a few seconds it will shut down. Then unplug system and push the power button down with it unplugged then replug it in and power up again. Then do a proper shut down again to see if the problem fixed. I hope this assisted you. John

Sounds like you have a bad picture tube. More than likely the CRT could be shorted, which would cause the set to shut down.
My first advise would be to power up the set with an isolation transformer with the voltage about 60% approx. 72 Volts AC, and monitor what happens when you increase the voltage slowly.
If the set remains on at 60 -70 %, then when increased to 90 - 100% it shuts down, you have something drawing too much current ( which could be the CRT )

Does the power light stay on? If so, you have an inverter problem. If the power light goes off, you have a power supply problem.

I need the serial #, to better assist you 
Thank you

The most comon cause is a faulty mode switch.

Solder, solder, solder! Shut down circuits protect crts to avoid permanent damage. If any of the deflection circuits are defective, or intermittent, shut down occurs. I have not only seen bad solder on deflection circuits, especially vertical, but also intermittent connections on the yokes themselves. I've also seen shorted convergence ics cause shut down. Don't forget solder connections in the power supply.

sounds like power fault but shouldnt be too expensive to repair,get local service center to check it out for you.,