Here is what I've done on my M96 to revert to the original Artatech firmware:
1 - Dowloaded the firmware from the site and unziped it,
2 - Dowloaded the mfgtool from this thread
https://www.mobileread.com/forums/sho...d.php?t=255435 ( M96_2014-09-30_21-42_1.6.4_7efa90c_user.7z ) and unziped it
3 - Copy from the firmware folder to the folder Profiles\MX6SL Linux Update\OS Firmware\files\android (MFGTOOL) the files u-boot.bin, boot.img, recovery.img and system.img in there
4 - Copy from the firmware folder to the folder Profiles\MX6SL Linux Update\OS Firmware\files\logo (MFGTOOL) and place the file uboot_logo.bmp in there
5 - run "adb reboot dowonload"
6 - run the mfgtool2
The installation sequence file is the Profiles\MX6SL Linux Update\OS Firmware\ucl2.xml , this has all the operations done by the MFGTOOL.
This worked for me on the M96, I don't know how the M92 works, but I hope this helps.