Make sure that the warranty period for the computer has come to an end. Disconnect from the laptop power supply and all peripheral devices. Remove the battery.
If the button is located under the false panels, pry it with a screwdriver and remove. You will find a charge on which there are controls and LEDs. With the right size of the button will set it to replace the old. When soldering exclude the circuit conductors between themselves and only use a neutral flux. If spare buttons are no solder parallel to the two existing Explorer and print them out. To do this, carefully make false panels, two thin holes. Install it in place.
In some laptops the power button is located on the side. In this case it is soldered into the motherboard. To access it, dismantle the computer: remove the caps over the fixings of the display, disconnect the cable, under the false panels, carefully remove the keyboard and disconnect the ribbon cable, loosen all screws in the bottom cover, and then remove the front. Solder the two conductors parallel to the button and print them out as described above. Assemble the laptop in reverse order. If you never disassembled the laptop first time it is better to do this operation together with a qualified professional.
Refit the battery. Connect the notebook to peripheral devices and the power supply. To enable it, take a screwdriver with an insulated handle and short out the printed conductors between them. The screwdriver and hold the handle, not tip. Do not touch simultaneously derived conductors and earthed objects and devices, which is not connected electrically with the body of the laptop - it can cause a nasty electric shock due to leakage of voltage.