Hi
I dont know.
I would try to power off via the PWR button, hold for upto 10 seconds. If that failed try removing the power cord and allowing the battery to run down in the hope that it will fail.
I have alternate media to install a new Operating System, and would have a DVD and or USB stick loaded ready to go. You could get a new OS from Microsoft and create your own media.
Then with the power cord re-attached I would start and IMMEDIATELY try to enter BIOS setup.
Get the boot sequence to use my OS media and proceed from there.
So what do you feel capable of trying?
