I switched on my Go 5000 the other day and got the message 'no maps found - please install a map' or similar. I plugged into my computer (windows) and tried to update via MyDrive Connect. It didn't recognize the SD card in the device so I couldn't install the map (Europe). I installed a smaller map on the device. This then enabled me to access the device and reformat the SD card (the same one that's been working fine till now). It still wasn't recognized so I did a factory reset. Finally the card was seen by MyDrive and I went to install the Europe map on the card. It downloaded, went most of the way through the update process but then I got the message 'update failed'. So far I have tried:
Uninstalling the 'corrupt map' left on the device
Retrying the update
Clearing the cache in MyDrive and updating again
A different SD card
Another factory reset.
Always the same 'update failed' message.