Make sure the SIM card can be used with the new phone. Some are not compatible. If you have this problem, copy the contents of the SIM on a PC or Tablet and then copy the file to the new SIM. Hope all comes out ok.
I assume your HTC phone is running Google Android. And here is a guide about how to recover Android device data, it will help you retrieve the contacts and data. How to recover lost deleted Android Data
Hi
Any short circuit on the PCB due to water intrusion causes short circuit in the supply voltage to the back light.
Try to clean the PCB under a microscope.or replace the damaged parts.