After booting up the lap top shuts down after about twenty seconds ????

make sure to SAVE current setting first before exiting.

Press and hold the power button for twenty seconds. This will shut down the Kindle. Press and hold the power button again until it starts to boot back up.

Overheating When the CPU overheats then it will shut down (i.e. thermal overload) and won't boot up again until it has cooled down. If this is the problem is not fixed then the CPU will eventually fail.
A faulty fan causes the problem or the fan and heat sink assembly are clogged with dust.
Check the CPU fan to see if it spins freely, if not replace the fan.
If the fan and heat sink is clogged with dust the remove the dust and make sure the vents are clear and dust free. Use a small brush and can of compressed air to do this.

Remove the battery and the AC adapter from the laptop.
Press and hold the power button for 60 seconds then let go
Plug the AC adapter only back into the laptop
Now press the power button on the laptop
If it now boots properly shut down the laptop and insert the battery
Now push the power button again
If it now fails you may have a bad battery

Hold the power button down until the Laptop shuts off completely and then pull the battery out for 30 seconds as well as the AC adapter.

Replace the battery and boot the Laptop

press the fn key on laptop hold it down and then press the power key on the laptop. once u see any display on the screen you will get some tests running on the screen. The system will show you the error message which u need to note down. else you can do a Flea Power on your laptop. Remove the adapter and the battery and then press the power button and hold it down for 30 seconds then connect the battery and adapter back and try to turn on the laptop. See if the magic works for you

hi you need to press the FN and F8,9 or 10 repetedly to restore it to default settings.

Try removing the battery and starting up only on AC power. You may have a faulty battery. It could also be the power supply or a bad memory chip. If it's none of these, then it's a motherboard problem.

Try booting into safe mode with CD-ROM support. Once you boot up to the Vista Desktop, restart the machine.

can you boot with the AC adapter? maybe the battery is completely dead.