Shuts off and on by itself as if the power buttons is stuck

Reset this device? In the event that the device freezes, you can force the device to shut down byholding the Power button for 15 seconds.? If the Power button does not reset your device, use the " pinhole reset"button onthe device.
I don’t know if it is possible with a USB with Windows image on it to repair, then it should be a bootable USB and the nextbook should be able from bios to boot from it.

Please provide the make/ model of your device.

Don't know this exact server. But my guess it is either a heat issue or a power supply issue. Turn it on with the cover off. Check the CPU fan(s). If your CPU is getting too hot the system might be shutting down power to save it. If everything seems cool it might be the power supply I have seen it when the power supply fan goes out on the power supply and the caps inside start to sizzle. Voltage ramps up and fail.
Hope this helps.
Also, Something that has tripped me in the past. Make sure the power button is not stuck. I had a server that the power button stuck down and it would turn itself off. Took me 2 CPU fans and a power supply to figure that out. LOL

By holding the power button down for about 10 seconds it rebooted

This solution may sound stupid, but it is affective. Try to press really long time (about 1-2 minutes) on the power button of the laptop. wait for it to shut down completely. Then turn it on to see what happens.

What may have caused this is an update of any sort.

Don't use the power button on the t.v. itself to turn power on or off. Use the remote. The power button actually gets "stuck" and causes the t.v. to turn on and off, seemingly at its own accord. Make sure the button is all the way out and flush with the cabinet, then just use the remote to power on/off. Hope this helps.

Its not a problem. Just replace the drained out batteries with the fully charged batteries and press the power button once again. The camera would shut itself down.

hold down power button until your machine shuts off. then power back on. you should be fine. if the cd is stuck in the drive, restart the machine and hold down the mouse button while restarting - the cd should eject itself.

Seems to be the power button is stuck on the tv itself

First try turning the TV on from the Power button the set itself (assuming it has one).

If not, unplug the TV from the wall, wait a half hour, then plug it back in. It should come back on.

Also check that none of the buttons on the remote are stuck down, and that the batteries in the remote are OK. The toy might've stuck a repeating button down (like volume) which may have then drained the remote's batteries.