Tinkering OpenWRT (20) : Flash Compiled Image

Step 1: 

After compiling, the bin file should be located in :
openwrt/bin/ramips/openwrt-ramips-mt7620-XXXXX-squashfs-sysupgrade.bin

Step 2:

Copy the bin file to board 
scp openwrt-ramips-mt7620-XXXXX-squashfs-sysupgrade.bin root@192.168.1.1:/tmp

Step 3:

Login board, ether via UART or Ethernet

Step 4:
cd /tmp
# make sure the file transfer is completed 
md5sum openwrt-ramips-mt7620-xiaomi-miwifi-mini-squashfs-sysupgrade.bin 

mtd -r write openwrt-ramips-mt7620-xiaomi-miwifi-mini-squashfs-sysupgrade.bin firmware

Wait for it to finish...

ref:
https://my.oschina.net/u/3258476/blog/835101
https://my.oschina.net/u/3258476/blog/836891