UniFi – TFTP Recovery for Bricked Access Points
Introduction
The method described in this article should help recover a “bricked” or unresponsive UniFi AP (Wireless Access Point). This method will not void the device warranty, whereas opening the chassis for serial TTL will void your warranty.
Most software-based issues will be resolved via this procedure. If your issue continues unresolved, it might indicate a hardware issue that cannot be resolved via software. Feel free to contact support (support@ui.com) if you believe this to be the case.
Method
1. Prior to beginning the TFTP recovery, download the firmware for the device needed by visiting the UniFi Downloads page. Navigate to the Unifi Access Point in question using the menu on the left.
2. Once the correct firmware has been identified, download it and save it to your computer. Confirm you are downloading a .bin firmware file. You will need to know the exact path to your file, so for this example, we are going to move the downloaded firmware file to your user home folder for convenience /Users/username/.
3. Locate the ethernet cable connecting the Access Point’s power injector into your switch or router. Disconnect the cable from the switch/router and plug the loose end into your computer instead. Now go to System Preferences > Network and set your computer’s network IP address to 192.168.1.25, subnet 255.255.255.0 and gateway 192.168.1.20.
User Tip: Take note of your IP address settings before changing it. You will have to revert back to the original settings on step 12
4. On macOS Open Applications > Utilities > Terminal and type:
tftp
5. A tftp> command prompt will appear. You are ready to reset the UniFi Access Point (AP) and connect it to your computer, while it’s in “upgrade mode”.
6. Unplug the primary (may be labelled main / master) ethernet cable from the UniFi AP.
7. Using a paperclip, press and hold the UniFi AP’s reset button. Make sure you can feel it being depressed by the paperclip. Do not release the button until step 9.
8. While keeping the reset button pressed in, plug the ethernet cable back into the AP. Keep the reset button depressed until you see the device’s LED flashing in upgrade mode (read about LED patterns in this article). This may take up to 25 seconds.
9. You may release the reset button. Now the device is in TFTP transfer mode.
10. On the TFTP command line in Terminal, paste these four lines and hit enter:
connect 192.168.1.20 binary rexmt 1 timeout 60
11. Type the command put followed by the path to the firmware downloaded in step 2 and hit enter. Following the example mentioned in step 2, something similar to this would be typed into the Terminal window:
put /Users/Alex/BZ.qca956x.v3.9.27.8537.180317.1235.bin
IMPORTANT: Remember you must substitute the bolded path and firmware file name with your own path and file name. A quick trick is to drag the .bin file into the Terminal window to auto-fill the full path to the file
Once it is successful, you will see something like this in the Terminal window (bolded words will be different for each user):
tftp> connect 192.168.1.20 tftp> binary tftp> rexmt 1 tftp> timeout 60 tftp> put /path/firmware.bin Sent x bytes in y seconds
The file should begin transferring at this point. The firmware will upgrade and the device will automatically reboot once it has finished. Do not reboot it yourself.
12. Re-connect the PoE injector’s LAN cable into your router. Restore the network IP back to what it was before.
Source
https://help.ubnt.com/hc/en-us/articles/204910124-UniFi-TFTP-Recovery-for-Bricked-Access-Points#3
