log in to routerOS webfig, setting those step 1, 2, 3. and then shutdown.. set ip static..put your ethernet cable on port 1, power it on then open tiny pxe, pick the initframs.elf image and press online.. remember disable virtual port ethernet, wifi etc except port you use it.. after sending succes.. disable port ether, klik tiny pxe offline, set ip otomatic and then plug in to port 2.. login and flash sysupgrade
i use tiny pxe from this tutorial for debrick..Xiaomi Mi Router 4A Gigabit Edition (R4AG/R4A Gigabit) -- fully supported and flashable with OpenWRTInvasion