[Cecil]

Originally Posted by Joe Wilson

We have to resort to the command line version once the jag light starts refusing to turn on. The GUI version assumes there is no jag connected and won't let you update, whereas the command-line version lets you force it to try to update, which worked for the first one.

This is because the Jaguar has gone into recovery mode. When there is no light on the Jaguar anymore, yet it is being powered, select (IIRC) Recover Firmware instead of Update Firmware. It should still be under the File menu. Make sure it is the only Jaguar connected when using this method, and it should recover itself.