Didn't get no black screen.
This was the procedure I followed on my Macbook Pro.
1.Downloaded the Line 6 updater to my Mac.
2.Connected to the Amplifi via USB from the Mac.Put Amp in update mode.
3.Opened the Line 6 Updater Application on my Mac.
4.Signed into Line 6 account, followed the instructions.
5.This then presented me with a picture of the device to update.
6.Then factory reset.
Updated, took about 10mins,job done.
Had a good play last night,connection dropped out a lot and had to reboot both App and device several times.
Hope this isn't going to become the norm, or it's going back.
It is a great amp apart from the connectivity issues STILL, that's already been well documented.