Zune detects nothing for my phone (Dark Knight Lumia 900 on MTN) It simply says "Your phone is up to date" "Current phone software version 7.10 (8779)" and it should be 8858. I've tried the Zune disconnect trick about 50 times.
Step by step instructions to force the Windows Phone 7.8 update
Connect your Windows Phone to a PC and launch the Zune software
Click on Phone > Settings > Update.
Allow the software to tell you whether an update is available. If so, skip this guide. If not continue to the next step.
Time to force the update.
Click another button (any of the options above or below the word Update).
Then click the Update button again, and this time disconnect your computer from the internet after 1-2 seconds. Do this by pulling out the Ethernet cable, disabling Wi-Fi, etc.
If it says your phone is already up to date, you didn't disconnect quickly enough and need to try this step again.
Wait 30 seconds or so and Zune should display a notification that an update is available.
Now reconnect to the internet and continue with the update process through the Zune software.
Depending on what OS build you are starting with, you may be prompted for several OS updates
Let the phone update and wait. The final OS build is 8858.
If you are getting just 8779, you'll want to repeat 1-4 above
You may also be prompted to install a firmware update at the very end, follow through with this
Celebrate! The whole process, including backup could take up to 60 minutes. Check that you are on build 8858 to see if you are done.
I first switched off the wireless setting on my phone.
Connected the phone to my PC using the USB cable.
Zune software is then launched.
Logged into my account.
Went to settings and clicked on update.
As soon as I clicked on update I then counted till 4 or 5 and disconnected from the internet.
Message popped up saying that an update is available.
Reconnected to the internet and did the update.
There are three updates that have to be done with the last one being the longest.
You just have to mess around with the 4-5 seconds thing to get the timing right.
Bit of patience required.