UBNT UniFi AP (UAP) Upgrade Loop
1. Forgot device from UniFi
2. SSH to UniFi AP (default credential ubnt/ubnt)
ssh root@ip_of_unifi_ap
3. Upload latest firmware image from UniFi web site (https://www.ui.com/download/unifi/unifi-ap)
cd /tmp
wget https://dl.ubnt.com/unifi/firmware/BZ2/4.0.15.9872/BZ.ar7240.v4.0.15.9872.181229.0259.bin --no-check-certificate
mv BZ.ar7240.v4.0.15.9872.181229.0259.bin fwupdate.bin
4. Run upgrade process
syswrapper.sh upgrade2 &
5. Wait a moment & adopt device in controller