Retevis RT3S Stuck On 446.00625 Mhz

If your Retevis Walkie-Talkie RT3S is plugged in at 446.00625 Mhz, this is not a malfunction. It is an undocumented feature.
RT3S is a dual-band uhf / vhf radio. It also has digital communication capability at the same time. Available as a DMR radio. Ham Radio Operators may buy this radio. However, it can be used as a commercial radio too. 

My radio suddenly failed to reach the relay last month. No matter which channel I chose, it always transmitted at the same frequency. First of all, I use a frequency counter to read my transmit frequency. 446.00625 mhz uhf and 149.02500 vhf. Regardless of the channel registered in the device, it does not transmit at any other frequency in uhf and vhf. To check this situation, you must first switch the device from CH mode to MR mode. You may follow photos to do this.

First I thought the radio was bricked. I thought the discharge of static electric might smoked my device. So I put the radio in its box and put it in the closet. Then TA2LUE Erol told me, TB8HSO Hakan from Gaziantep updated his firmware and uploaded his file by using CPS software to correct his situation. I did what they said. But I couldn't fix the radio. Then I got bored and I thought of trying different key combinations. I have tried some random combinations. Bingo! Found it. I decided to share it to anyone  who needs it.

You can use this key combination to solve this situation.

M + Power On.
The radio returns to normal use.
Good Luck!