I had the same thing only after 24 hours it was still stuck on 36%!
When my system was installed the engineer used some Devolo network plugs to link my system to my network as it did not come with Wifi. This has always caused me problems and copying the original music onto the system took so so long.
I could have invested more money and upgraded the plugs but I had already spent a great deal and then realised I didn't need the BS5 at all - the BM5 has all the navigation and my TV could have acted as the BS5. A warning for other perhaps.
I finally solved it this morning by linking one of the PCs via the plugs, moving my router closer to the BM5 and connecting it directly to it via a CAT5 cable. My other PCs are all wireless so this presented no problems and my printer also connects wirelessly so aside from an hour of cabling it was a smooth transition.
I then ran the update and it went through in a few minutes.
With bated breath I expected great things but sadly not even the information message had changed. So a massive amount of work for what.
Having bought B&O since the early 80's this is the first product I can honestly say that I regret buying! In my opinion it was just not ready for release.