Weird problem with new s4

Hi, I sent my old s4 mk2 over to Germany to be repaired some months ago and just set up the new one i received yesterday. The problem is when I move the platter it makes a jumbled up digital sound and when the music is playing the nudge function doesn't work. I thought it could have been the 2.7 update but I tried the 2.6.8 backup and it was the same.

I presume it was a new unit they sent me back because the serial number was different from my original unit.

Any help would be appreciated.

Thanks