My phone is not turning on

Try with a new battery.

At the firest you should check if the problem is from it's software or not. I mean flash it first. If it wasn't use full, You should connect phone to power supply (instead of battery) and see how many current it is getting. If it was to many over than 2 A, seperat the phone. By the heat crates you can find the defective component.

If it takes another amperes like 0.12 A also by chasing heat, You can find the defective component. But it is hard to find the heat if the amperes is less than 0.1 . Now you should wait for 15 minutes and then find the heat whit your down lip ?.