Hey my iphone was recently water damaged and for the longest time it didnt turn on. my friend put in a cheap dock connector and a new battery. with the baattery in it turned on and was working, i could even sync it and play music, the problems were that it didnt read my sim card, or charge the battery. some dude said he could fix the charging problem for 40 bucks. i was wondering if i could just fix it myself

what could be the problem/ what parts do i need to replace