Xiaomi Router 3G - How can i back to stock?

I install openwrt on Xiaomi Router 3G.
But, its more stable to stock, at least for me.
How can i back to stock Xiaomi filmware?

Taken from: https://openwrt.org/toh/xiaomi/mir3g

Recovery to stock for R3G

Assuming you used the above installation instructions you will have a stock kernel image in system 1. If it can be booted then it may be used to perform a stock firmware recovery, thus erasing OpenWrt completely. From a 'working' OpenWrt state (even failsafe)

Failsafe only:

  1. run: mount_root

  2. run: sh /etc/uci-defaults/30_uboot-envtools

  3. Then do the steps for 'All'

All:

  1. run: fw_setenv flag_try_sys2_failed 1

  2. run: reboot

The board will reboot into system 1 (stock basic kernel) and wait with system red light slowly blinking for a FAT formatted usb stick with a recovery image to be inserted. Press and hold the reset button for around 1 second. Status LED will turn yellow during recovery and blue when recovery complete.

My english is not perfect so i will ask probably a couple of times until i will not be sure, i hope everyone will understand.
For now i have 3 questions:

  1. Should i start with Failsafe or All?
  2. Should i do this in Putty?
  3. What i should put in usb? stock filmware? .bin?