First off: I am very unknowledgeable with coding. I knew this going in.

I built a PiPlay for my girlfriend who, for as long as I have known her, has lamented the loss of her NES. So I figured I would make an attempt to build the PiPlay with a Raspberry Pi 2 Model B and put all the NES ROM's on it as a gift for her for Christmas. I got it working perfectly. I even got a case printed that looks like a tiny NES box. She was so happy.

We started it up at her place, and there was no audio. No Mario theme music, and when we went to run a ROM, there was no audio either. She has the audio coming out of her TV through HDMI (we tried other devices and it worked just fine). And we then hooked up the headphone out from the Pi and still couldn't get audio to come out to the TV.

I took it home and plugged it in and it immediately worked just fine. Same setup. Audio is coming out of HDMI to my TV same as hers. I did not supply her with an HDMI cable, we used one of hers, and we tried two different cables to make sure one wasn't faulty but couldn't figure out the problem (and yes, we made sure the TV volume was up as well as the menu system volume). Can someone please help me identifying the cause? I knew I would be a bit over my head since I don't have the skill set for this, but I'm so close to it being perfect that I don't want to give up right at the goal.

Thanks.