"do you power your Garmin from your TM batteries?
If any of those are true, you may have blown a fuse inside the TM head"

Oh no Cat Fan... ys I run the TM and the Garmin from the same battery. Is it difficult to access the fuse? Can't run the 2 from the same battery in the front? I'm running out of space to put batteries. Gotta love electronics... when they work!