Hi, I've successfully installed and configured OpenWrt 19.07.5 in an Ubiquiti Unifi AP Pro, but now I want to restore the original Ubiquiti firmware to try out some things.
The wiki page for the AP Pro links to a "Harder Soft-Unbricking a Ubiquiti Unifi UAP-Pro AP" page describing a method to restore the original firmware if the device is bricked. However, my device is not bricked so opening up the device and attaching a home made cable that I don't currently have seems like more work than should be necessary.
So I'm wondering, if I ssh to the device, can I somehow connect to the serial console then and use the mtdparts, erase, saveenv, protect commands etc.? When I ssh to the device I see there's a /dev/console, so I used opkg to install minicom, but I could not get anything working (115200, 8N1, and a variety of hardware/software flow control combinations didn't work).
Is what I want possible, or do I have to make a serial cable after all?
(Or, ahem, does anyone know of another method to restore original firmware to a Ubiquiti Unifi AP Pro?)
Ubiquiti is very easy to return to stock with TFTP recovery. The process is the same for any of their APs.
Static IP your PC to 192.168.1.10. Ethernet switch in between the AP and the PC is recommended.
Hold down the reset button while plugging in the AP power. Keep holding until the LEDs blink alternately.
Use a TFTP client to PUT the stock firmware to 192.168.1.20. This must be done within less than about 30 seconds after the LED started blinking.
Wait for AP to flash itself and reboot.
No, when you do this just the data goes across it should not matter to the receiver what the file name is. But to be sure just use the name it was downloaded as. You can run tftp from your Downloads directory. On Windows 10 open a Command Prompt (not as Administrator) and:
tftp -i 192.168.1.20 PUT filename
If this is unknown program error go to Control Panel, Programs, Turn Windows Features on or off, scroll down and check the box for TFTP Client.
Someone else has already told you how to deal with your problem, and you should do that.
I'm just going to answer the question in the title to give some background information.
The serial console you are trying to access to write those commands is the uboot (bootloader) console.
The bootloader is a very small firmware used for recovery (the TFTP recovery procedure is provided by the bootloader) and startup, that is executed only when the device is powered up, it goes and loads the actual device firmware or does a recovery action, then shuts off until next time.
The only way to interact with it is to connect a physical serial console to the device, connect the power to the device and interrupt the boot sequence with the serial console, if the device has completed the boot sequence and is running OpenWrt or the device's stock firmware, the bootloader and its console is not accessible anymore.
Most devices nowadays have some form of recovery procedure and don't require serial console or interacting directly with the bootloader.