Hook it to your main router box with an Ethernet cable.

Try closing and restarting the controller. Sometimes I’ve seen this “stall”, but the update was complete. 

Thanks

Tried both still not working … 

So, I bought a refurbished port, which arrived yesterday. I had the same issues, first trying with WiFi, then wired. I would get 3/4 of the way, then it wouldn't move even after a couple of hours. Closed and re-opened the app, and it got to beyond 3/4, so I left it overnight, but alas, it didn't complete. I saw advice of restarting the port and router (unplugging both for 10 seconds), and when I went to update, it completed the wheel, but didn't complete the update. So, again I retried it, even plugging in 2 ethernet cables, and on another router and port reset, it finally worked! I don't know if it was the double ethernet cables or what, but I'm not going to argue! 

It then didn't want to register the first time I tried, it showed up as a device, but then wouldn't link to my account. 2nd time was the charm for that. It then took me a while to work out how to get the turntable working with my surround setup, but after an app restart the line-in option is now all working. 

A stressful 24+ hours, but it's finally working and I am happy. I hope you're able to get yours updated and my trials and tribulations help.