The screen doesnt lit up

Hey der , I have small query

Own a HTC 10 and I screwed it up trying to make myself a diy Bluetooth speaker , and tried to get to the store here and they seem to have no idea what went wrong as the phone works fine calls incoming and other notifications, but the screen doesn't lit up but wen the same screen is put on a other device it does lit up . The stupidity what I did was to to provide a 12 volts power through the 3.5mm jack . The Jack works fine tried it with the headphone music plays and aswell I can recive the calls . Now wen we tested it with a different screen also it doesn't seem to lit up . I hope you could help me with what exactly I should be looking into . Thanks