I recently came across a Javascript bug that was preventing firmware updates on the Edgemax POE through the GUI. Updates, therefore need to be completed through the CLI.
The router supports holding two firmware versions at once. This means it can hold a live version and either an new updated version or an older version to roll back to.
SSH to the router with your username and password
Display the current version
show version
Download the required system image (this address can be found on the Ubiquiti site) this address is for version 1.5
add system image http://dl.ubnt.com/firmwares/edgemax/v1.5.0/ER-e100.v1.5.0.4677648.tar
Select yes when prompted to replace the old version
If all goes well you should see
Upgrade completed
Run the following command to see which firmware versions are stored on the router
show system image
You should see the following text or similar
The system currently has the following image(s) installed:
v1.5.0.4677648.140620.1301 (default boot)
v1.4.1.4648309.140310.1607 (running image)
A reboot is needed to boot default image
The new version will be loaded automatically on reboot
Restart the router
reboot
y at the confirm prompt
To rollback to a previous version
Run the following command
set system image default-boot
This will switch to the other firmware version on reboot, regardless of whether it is older or newer. Answer yes when prompted
To delete the non default boot image
delete system image
Happy upgrading!