Audio/Nav not working after battery change

[Jerry A]

My son in law has a 2016 GX460.  Battery died when my daughter was out and about.  she had it jump started then went home and my son in law installed a replacement new Battery.  Now the radio and nav is not working.  at first the ac wasn't working at all also.  we read some on line and this seems to be a common problem with lexus.  We checked all fuses and tried disconnecting the Battery, all hints and tips we could muster.  Now the ac seems to work but still not radio/nav.  camera displays when in reverse.  Any additional info or suggestions would be very welcome and helpful.  Thank you in advance if you can help please.

[Amint]

I have the exact same problem happening in my 2016 Lexus RX350. Battery was replaced by a certified mechanic because Lexus Dealership had a 2-week back order on OEM batteries, so they told me to do it elsewhere. The Certified mechanic replaced the Battery and everything works except the Media Unit. Back up camera comes on in reverse but the radio/NAV seems to be completely offline. 

I took the car to the Lexus Dealership in Richmond Hill, ON, they acted like they had never seen this happening before and charged me for diagnostics because in their words this has had never happened in their expertise. While there is 1000s of online complaints on the same exact issue on Lexus IS and ES on the 2014 to 2016 models. Apparently the radio system is Pioneer and their model has clear manufacturing defects that at the time of Battery replacement the radio completely dies on some models. They are trying to charge me $9,000 to replace the entire radio system because my warranty ran out 6 months ago. This seems to be a serious recall that Lexus has to do but they are avoiding the situation by blaming others. 

Please, if you have found a solution let me know as well as I am not trying to spend $9,000 on a radio unit and I cannot sell this car in this condition either.