- Retrieve the Openwrt firmware first: https://downloads.openwrt.org/snapshots/targets/mediatek/mt7622/openwrt-mediatek-mt7622-totolink_a8000ru-squashfs-sysupgrade.bin
- Press the RESET button
- Start the router
- Wait 10 seconds, then release the Reset
- connect with the browser on http://192.168.1.1
at this step you'll see this page :
https://i.imgur.com/YFXsQCl.png
Select the OpenWRT file and click Firmware Update.
You can use this process to go back to the original firmware at any time.