My Htc one M7 s heating and battery draining when ever i make or take a call!!!

i updated my phone using RUU, its running 5.0.2 , but i heats up like hell when i use the calling feature. what should i do ??? it goes upto 55 C & and cools back when i switch it to airplane mode!
My phone is unlocked (bootloader) and S off !! Plz help
Thanks in advance!!!!!