No matter what you do, you can't get your Nokia Lumia 635 to turn on. Here are some things for you to look at:
(1)Drained/bad battery
If your Nokia Lumia 635 won't turn on, especially if it has not been used recently, you may simply have a drained battery. Plug your Nokia Lumia 635 into your computer or AC adapter and see if anything happens. Ideally your Nokia Lumia 635 will recognize it has been connected to a power source and charge its battery. If it will no longer charge, the battery must be replaced. You can purchase affordable batteries online.
(2)Bad display
It is possible that it appears nothing is happening because the display is bad. If you hold the Nokia Lumia 635 up to your ear you should be able to hear the hard drive spinning and feel it vibrate. If the Nokia Lumia 635 sounds like it is working properly but nothing is visible, it is possible the display is bad and must be replaced.
(3)Bad Power button connection
If the Power button is not seated correctly, it is possible that the Nokia Lumia 635 will not turn on. Be sure that the bar on the Power button is completely flipped down to ensure a positive connection.