V7PRO Mars Downgrade to Original FW

[Mbentefor]

Hi!

What are some possible ways to revert to an original firmware when I've already installed Mars firmware?

What I tried:
Direct clicking on a bin file - "Invalid file"
Putting flash.bin into a USB root and continuously pressing Menu button while starting up - No reaction
Connecting onboard 3 pins (TX/RX/GND) to CH340 USB to TTL adapter - No application was able to recognize the V7PRO.

What am I missing?
Thank you!