did the mic and home button ever work? if it wasn't charging, sounds like you probably didn't get a chance to test them
the kid you bought it from said, 'it was totally fine and i dunno what happened but it was fine i swear and i totally would have repaired it but i was due for an upgrade so i'll sell it to you for $50 bucks'
AKA 'i dropped the thing in water and the bottom got wet and i grabbed it out really quick but water fried all the components at the bottom of it'
i know he said 'I SWEAR IT ALL WORKED BEFORE'
it did — when he took it out of the box