iPhone won't turn on after disconnecting battery and screen a few time

Hi,my iphone 5s won’t turn on after i disconnect the battery and screen a few times but before this it was fine sometimes it can turn on sometimes it stuck on boot loop and turn itself off after that but now it won’t turn on at all even when i change the battery and screen to the old ones that i had lying around.even when i tried to charge it,it still doesnt turn on but the back of my phone feels hot a bit when i left it charging so does that mean the logic board is still ok?can anyone tell me the reason cause i hope its not the logic board thats dead…