Hey. First of all check the old charing port if it got dust and dirt in the charing port. A needle usually works fine.
Test a hard reset, turn it off. Hold power button and home button same time for about 20-60sec, when you see the Apple logo let go.
If that dosent help i would check so the speaker is set down good, the upper part of the media speaker maybe isent set down good.
I hope it helps