Chosen Solution

so i bought a Iphone 6 from a friend with broken battery and screen i replaced them both yesterday, after i did so i wanted to turn on the phone but i had a black screen with the white apple logo, when i wanted to plug him in my pc itunes/my pc won’t recognize the phone. now this evening i had a sign telling me the battery was low. but still nothing. now it wont even turn on after charging for a couple of hours nothing more… what can i do?

Sounds like Tristar (u2) issue where not charging battery and not connecting to Itunes are classic symptoms