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. Preferred Ham Radio buys this radio. However, it can be used as a professional radio. 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, the frequency meter measured this 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 see this situation, you must first switch the device from CH mode to MR mode. You can do this as in the photos.

First I thought the radio broke down. I thought the discharge of static electricity might have been corrupted. So I put the radio in its box and put it in the closet. Then TA2LUE Erol from Gaziantep said that TB8HSO Hakan updated his firmware and uploaded his file by using CPS software to correct his situation. But I couldn't fix the radio. Then I got bored and I thought of trying different key combinations. I came to this by chance. I am sharing with you.
You can use this key combination to solve this situation.

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