Thanks for the reply, Butters. I just acquired this nuvi form an eBay purchase, however, I have a number of these in the 1350, 1450, and 1490 configurations. I wanted to update some of the files through Express, but inadvertently upgraded the firmware to 6.30 at the same time. I don't like 6.30 as it loses the map detail at 200m zoom rate. So, I put the 5.90 GCD on a uSD, named as gupdate.gcd. Part way through the processs, the gps stopped responding, then I noticed that the uSD had popped out (not well latched, I guess). Since then, it is stuck at System Software Missing.

I have tried the cure process with both HWID versions of the firmware. The MTK version gives the message that there are no updates for your device, so I believe the 972 version is correct.

I do not have a backup of garmindevice.xml, but will try g7towin.