My iPhone is not booting or holding charge.
My friend gave me their old iPhone 6+. It's pretty messed up physically (smashed screen, bent body, dirty ports etc.) when I plug it in to charge it shows the apple logo and the charging icon but even after a whole night of charging it didn't hold anything or boot. I have opened it up and it's quite dirty in there as the seal has been broken but I don't think there is any water damage. I have watched a lot of repair videos in the past but apart from those I know nothing about phone repairs.