I have recently completed the upgrade to my Rosetta unit. I decided to re-use my existing SD card, so copied the old software contents onto a hard disk back up as a precaution. Then carefully followed the procedure set out on
https://pilotaware.com/wp-content/uploads/2016/09/160901-Manual-Software-Upgrade-1.pdf Then inserted the SD card into Rosetta and waited. Even having left it for several hours, Pilot Aware did not show on my list of wifi points.
Then removed the SD card completely re-formatted it again (per the instructions) copied the new software onto it again. Also took the precaution of cleaning the contacts on the SD card. Installed the SD card into Rosetta and powered up. It then started, the wifi network became visible and everything is working well. Took it flying this morning without any problems.