Caller can't hear my voice.Android 6 double din universal head unit

[AC Question]

I have successfully installed the 2-din unit.It worked great. After few days.When I make call inside the car, I can hear other party voice clearly. But they can't hear my voice.I have tested the "sound recorder" app. It record voice.I fix the external Mic also.No luck.

I need to hard reset head unit. I refer some youtube videos for key combination. Non of key combination work.Any one know about how to take this to initial state?.

This I got from Aliexress. This is Bosion android 6 double din with power button on top left.

all ather work well except blue tooth call.This is very important feature.