Powers on by itself

Chances are you have a stuck button on the button cluster, what I'd do is remove the connector going to it and use the remote control, with a stuck button the remote won't function properly.

When heats up, the supply voltage from the main power supply board goes less. Check all the soldering to this board for any loose solder terminals. Resolder all the suspected solder terminals by applying a little more solder. If it do not help you, replace the board as card basis.

I had come home about a week ago and pushed the power button from my remote but my tv did not respond. So I just went to the front panel and pushed power but once the tv turned on, the volume was on full blast! I used the front panel volume decrease to get the volume down, but when I stopped pushing the button, the tv increased its volume to full blast again by itself! Naturally I just turned the tv off for a few moments. I tried the remote again, no response again, so I used the panel power button. The tv volume was still full blast when it turned on but after I decreased the volume it stayed this time. The picture is and has been perfectly fine and the tv was working fine. The next day the problem started all over and now once we turned it off from frustration of having to manually use the panel to change channels, it now will not turn on at all. I have changed batteries from my remote, reprogrammed my remote, pushed system reset several times, unplugged it for a while, bought a new surge charge, and even held the menu and device panel buttons for 10 sec and tried to turn the t.v. on again! What other options do I have or what may be the issue at hand and possible parts that may need to be replaced?? Thanks!!

You need to change the picture-size by using the TV remote and or cable remote.
On the remote look for P-Size, Zoom, Sreen size or Ratio.

go into programming mode and search for channels   it will do this automatically to find all antennae and all cable channels    if this is hooked up to a receiver box then only channel 3 will be found or used    also most tvs are computerized these days and at times it will need to 'rebooted'     unplug the power and wait 10 seconds and plug it in again    this may have to be done whenever you are locked out from changing channels or using the volume controls

switched HDMI plug from HDMI1 to HDMI2 port and that solved the problem

Change the tact switches

This is the common symptom of defected IC memory 24COxx,replaced this IC so it will works normal again.
Feel free to ask whatever the result...

Hope this may help you;

DON"T FORGET TO RATE:

Is your remote programmed properly? If it is a universal remote, try setting it to one of the different codes for your brand. Sometimes the power and mute buttons and things like that are the same for all different types of a brand, yet all of the channel and volume things are different. If it's the remote that came with the TV, then I would try to get a replacement, as it could be faulty. Hopefully this problem is with the remote, and not the TV. Find if this is the case by using the volume/channel buttons on the TV itself. If they work, then you can be reasurred you don't have to call the TV repairman, and you will probably be able to fix this problem yourself.