Phone device on steering wheel is preventing stereo volume
 

At this point since I've not seen the car it is a Mazda 3. Model not known. There is some sort of device on the steering that accommodates a cell phone. But the stereo has not volume. All speakers are there and hooked up. Anyone aware of a mute button, etc. such that the previous owner setup this steering wheel device? Thanks and I'll know the year of the vehicle later. I'm asking on behalf of the new owner who is a friend but lives a couple hours away.

Photos?

The only photos we have are from the large owners manual:
https://carmanuals2.com/mazda/3-2010...s-manual-30206

Chapter 6 and many pages on the entire audio system. It speaks to codes, etc. involving Sirius Radio and autopilot that engages based on the level of noise outside the vehicle. One fix from Youtube was the remove the 7.5 amp fuse for the radio, wait 5 minutes and re-insert and that got volume from the radio. We tried that. Currently everything works, CD player, radio, volume indicator up and down, everything works but no volume. And after looking at the car and reading the many pages from chapter 6 of the manual it is very clear that we are not intelligent enough to figure it out for this young lady who bought the car from a used car lot. She has no recourse as no lemon law in the state. There may be some code or password from that last "human" owner of the car but they are not known. The car went from dealer to dealer before it was sold to her.
As far as the steering wheel controls for the audio system there is only a volume control and a mode control.
Thanks.