If you have ever had to manage a UniFi Video NVR from Ubiquiti, you will know what a pain it can be to try to log back into your UniFi Video system after you perform an operating system update or firmware upgrade.
Several hours of chat with their support team could result in more frustration than necessary. The solution is simple unless the upgrade really destroyed your device and you require an actual factory reset or filing an RMA. All you need to do is hard reboot the device by pressing and holding the power button. Period. Then go back and try to access your device again from the browser.
You can thank me later.