Re: Phone doesnt switch on due to a boot problem.
Welcome to Windows Central.
There are at least three possible solutions that you can try:
1. Connect your phone to your PC and use the Lumia Software Recovery Tool to re-install the latest official OS for your phone.
2. Take your phone to a service center and have them diagnose and repair the problem for you. If your phone is still under warranty, the repairs or replacement of parts should be free.
3. Place your phone in a sealed bag of uncooked rice. This method implies that there is some moisture in the phone, and this method dessicates/dries the phone up such that it would work again. Although this has been reported somewhere in the internet and the user who described the method said that it worked for him/her, it seems that nobody else was able to confirm that this solution works.
As for me, when this happened to my L1020, only a service center was able to repair my phone - under warranty. Take note that if you mention that you installed an unofficial OS release in your phone, the service center may simply decide to not honor the warranty of your device, that is if your device is still under warranty.