how to hard reset bluetooth on m37x?

[fuzzysig]

my phone got stuck on sony bluetooth boomboxlast year ( it would not unpair from boombox no matter what i did)
and it wouldnt connect to the car radio
i reset my phone cleared cache and did everything i could
also reset the radio multiple times
but after that it doesnt work right.

it would freeze for like 5-10 minutes and then allow me to press play
the buttons are greyed out and screen says bluetooth stopped.

my phone connects normal to any other devices.
somehow it corrupted this car bluetooth system where it freezes now when connecting

[VStar650CL]

Before trying a reset, try unpairing and deleting both the phone from the car and the car from the phone, then re-pair. If that doesn't work, do a hard reset by disconnecting both battery terminals (negative first) and jumping them together for a minimum 5 minutes (TechLine recommends 30 to guarantee discharge of all devices and circuits in the vehicle). Then reconnect the cables (negative last). If the problem is firmware that's gone "off in the weeds", that will fix it. If that doesn't work, try rolling back the OS on your phone. Probably 95% of bluetooth issues are caused by the phone and not the car. Apple, especially, is infamous for moving the furniture in the iOS while no one is looking and then invisibly issuing a patch days or weeks later. Needless to say, it drives us technicians nuts.

[fuzzysig]

already did all that.
there was no software update. the bluetooth somehow got stuck on another device and would not disconnect even when i was out of range and tried to connect to car.
after that the car blluetooth somehow got corrupted. i reset it with shop scanner alreadyand deleted devices multiple times.
is the firmware in the bluletooth module or in the radio unit? I'm thinking of just replacing the bt unit with a newer one maybe it would fix it.

[VStar650CL]

It's both. The bluetooth stack is inside the telephone adapter, but the control function and memory firmware are all in the AV.