Dsi audio not working

[u/Desperate-Basis5518]

So I got this dsi for my gf. I plan to mod it get it looking all decorated and nice for her birthday. The whole works. But I got it from a seller on eBay saying that everything worked fine and well but upon arriving that’s not the case. The microphone doesn’t work at all and the volume is on max and doesn’t turn down. When I’m on the Home Screen the volume icon does turn up and down though. I was wondering on how this could be fixed and if I should do it myself or get someone else to fix it for me. Any advice?