We have just bricked a large number of QRT 5 AC panels by upgrading them to the latest bugfix ROS release.
One upgraded the Ethernet port becomes unresponsive.
I have attempted to Netinstall / downgrade by forcing a net boot holding down the reset. Still do not get a link light to be able to downgrade the QRT. QRT still boots and posts, as you can still hear the audible double beep confirmation but am not able to get a link via the Ethernet port.
A warning for people using the Bugfix ROS release not to use it on QRT - AC's