So far so good then. Format it with RMPrepUSB using only the settings shown in initial post here: [Only registered and activated users can see links. ].

Download the program from here:
Code:
Please Login or Register to see the links
After formatting, let it re-boot and set it to Mass Storage then connect to PC and load a basemap manually into .System folder because GE won't offer you a replacement. Either use the one from backup (gmapbmap.img) or for absolute safety download a fresh and updated file from here: [Only registered and activated users can see links. ]. Then start GE and see if it'll update normally.
Note: If it won't boot empty after re-formatting, return all your files and folder from the backup, delete the contents of the restored .System folder and try again to update with GE.