Already tried that But, No Luck.
I am afraid because Onkyo is not in my city and it is out of warranty as well.
Checked Onkyo datasheet where it said that wiring from MMP to buttons is NG.
i checked with multi-meter wiring was OK
My Onkyo HT-R494 front panel's all buttons including volume + Standby got Frozen.
It is luckily connected with TV with CEC HDMI ARC before it jammed so working fine with movie and audio.
But, cant change input and cant use any of the front panel buttons and also cannot be reset as buttons...