(Step 1) Shutdown and power off the computer.
(Step 2) Once the computer is powered off, unplug the power cord. If it is a laptop also remove the battery. It is important that any way for the system to keep getting power is unplugged or unhooked.
(Step 3) With the power cord unplugged and the battery removed (if you have one), hit the power button a few times as if you are trying to turn on the computer. When you do this and the computer tries to turn on, all the electricity is drained out of the system.
(Step 4) Plug the power cord back in and reinsert the battery (if you have one) and turn the computer on.
Once Windows is loaded you can continue on with the other steps and repairs.
This trick is used on all forms of electronics. Computers, cell phones, routers, modems, TVs, DVD/Blue-Ray players and so on.
Have you ever heard someone say their computer wasn't working right, so they unhooked it, took it to a computer repair shop and when they got there the system was working fine?
This is because the power had drained out of the system!