not charging well and when does stops its self

my phone does not charge when plugged in straight away and tends to vibrate when it starts charging but when this does eventually happen the vibration tripes something in the phone which stops it form charging thus there is every through seconds through out the night. the phone does eventually charge. my other problem is that the skrews at the bottom of the phone kept on coming loose so the skrews are scratched from where i have tried to tighten them up. this means that i am worried that Apple will not touch the phone as it looks like it has been tampered with but has not as they will realise if they take the screen off because the last time it was of the phone was in the factory thoughts please!!!!