There is a BMW Navigation forum here...post there. Nav upgrades are rare here given the newness of the E70.

On older navs I've had to wait for the drive to completely power down- like let it sit for 20 minutes with the car open, trunk open...the turn the key on simultaneously with trying to get the nav to work. (In that case it was eject)..

You might also reach out and beg for help from one of the vendors that sell upgrades for nav- Patrys comes to mind. Check out the forum. Also there is a E90 owners forum with a lot more Nav related content....

Update this if you get it worked out

A\

PS Sorry to hear- the whole Nav update thing is near and dear to my heart and I hate hearing that the BMW system is failing folks....