High pitch beep noise from speakers that will not stop

I have a 2007, 175k, replaced the 12v battery in January, and reconditioned the traction battery with 1 new module. It consistently gets 46-47mpg, running great.

Today my wife calls and I could hear it on the phone, as soon as she presses Start, there is a loud wine over the speakers, it does not stop, even as she drives it will not stop the loud beep/wine... There are no warning lights on, no ABS flashing, no triangle, no codes, no open doors. She left the house this morning and drove ~20 miles without issue, couple stops, then she gets in and it starts this beeping. The MFD shows the traction bat at 50%, it appears to drive fine.

I had her check the maint menu on the MFD, the 12v bat shows 11.9 volts, but this is probably a little low because we have been turning it on/off a bunch trying to figure this out.

Having her look for codes now, but no CEL was shown.

I have seen a few other threads about this, only useful info was to replace the aux battery, but it was new 8 months ago, I dont see how it could be shot already. If anyone else has seen this issue please let me know.

 

Codes pulled
01-db-190-df-f
01-db-190-55-9
01-db-110-F3-3

-190 are Head unit related (no idea)
-110 is MFD (no idea either)

Is the MFD bad?

 

I got home a bit late, checked voltage on my multimeter, aux bat shows 12.6v, plenty for me. I checked codes on Torque, no stored codes, but I guess it cant check more advanced bus codes.

I am hoping for some pointers to narrow it down to the MFD or the stereo, it definitely comes out of all the speakers, and while stereo can still play in all modes, wine still comes out.

I shot a short video of the it if anyone wants to hear how terrible it is:

 

Car had been off for 2-3 hours....

Anyways a trip to pick-a-part, and a new stereo solved it....

Thank God it wasnt the MFD... of the 8 prius in the yard, 3 had arrived that SAME day - NONE had MFDs.

 

just the head unit, not the JBL, so no amp, no changer.