Recently I’ve been asked to write a tutorial in English on how to update a Nokia Lumia to Windows Phone 7.8.
This is the official update (not a Cusom-ROM) downloadable for everyone on the Nokia-servers via NaviFirm.
We successfully flashed Windows Phone 7.8 on our Nokia Lumia 610 and we wanted to provide you this piece of information.

Before we start – FAQ

If you are doing this for the very first time, you should take you time and read the whole article carefully. Else you could make a mistake or overlook a warning and risk to brick your Windows Phone device. All your data is wiped during the flashing, so you should create a backup of all your files on your PC. If you have your photos and contacts synced with SkyDrive, this won’t be necessary. The photos uploaded to SkyDrive are always resized, so better back them up on your PC. 
We hope that with this tutorial even beginners will be able to understand it.

Needed Software

Firstly you need NaviFirm, which you can download here.
With this tool, you can scan the Nokia-servers for the update and choose the correct firmware for your device.
Secondly, you will need a tool to flash you smarphone with the latest version of Windows Phone 7.x. For this purpose we use the Nokia Care Suite 5.0, that you will need to install on your PC.

In case you don’t own a 4Shared-Account, feel free to use our data to log in:

username: downloadwparea@gmail.com
password: wpareade

If you haven’t installed the Visual C++ packs yet, you will be promted to install it. For NaviFirm you will also need the .NET Framework version 4.0.

Connecting the Windows Phone to the PC

As soon as the installation has finished, you start the Nokia Care Suite and choose and open “Product Support Tool for Store” at the application launcher.

In case your device is not recognized by the Nokia Care Suite, you will need to install the driver found in following path:

“C:/Programs(x86)/Nokia/Nokia Care Suite/Driver“
You need to install the WinUSB(x64/x86) drivers, depending on your operating system. 

As your device is connected and recognized correctly, you see the info at the right side. Now you must write down the Product Code of you device. This is really important and you will need it later.

Now you’ll have to create the downloadpath. In the end it should look like this:
C:/ProgrammData/Nokia/Packages/Products/[DeviceType]

The device type of our Nokia Lumia 610 was rm-635. It is shown also in the NCS. Make sure that the name of the folder is written in lower-case letters.

Downloading the Firmware

To get access to the Nokia-servers you need to launch NaviFirm. On the top-left corner you see a dropdown where you select “Nokia Care Suite”. Now you see a list of devices. Browse for your Windows Phone, you can find it easier by using the search bar below. We used the german version of the firmware on our Nokia Lumia 610 bought in Austria, it doesn’t matter which version you choose, but we recommend you using the version of your country.

Now you select the downloadpath we created previously and deselect the cross at “User Product Code as final path”. Now you just need to hit the download button.

Following step is really important: Copy the ProductCode you wrote down before and replace the ProductCode on the downloaded files with yours. (like in the picture below)

Explanation of the process:

On the right side of the Support Tool you see a “Basic Info”.
You open it and you see a ProuctCode. My product code was 059P349.
Now you click on the line and press ctrl + c.
Thereafter you create a Word document (or a txt file) and paste the code in it.
After you downloaded the update from NaviFirm, you see 3 files with a similar code like yours.
These are following files:
RM835_PorductCode_1066.0000.8858.12470_010_signature
RM835_ProductCode_1066.0000.8858.12470_010.vpl
RM835_ProductCode_1066.0000.8858.12470_010.dcp

In these files, where the other ProductCode is, you replace them with your code. This needs to be done, so that the NCS thinks the update is for your device.
In the end the files should look like this, but instead of my code you have to copy your ProductCode of course.

RM835_059P349_1066.0000.8858.12470_010_signature
RM835_059P349_1066.0000.8858.12470_010.vpl
RM835_059P349_1066.0000.8858.12470_010.dcp

Finally – Flashing the OS

Now you need to launch the Nokia Care Suite again and start the Product Support Tool. Click on “File” in the top-right corner and go to the “Preferences”. Now add the downloadpath we created previously.
The files you downloaded and edited should be here:
C:/ProgrammData/Nokia/Packages/Products/[DeviceType]

Furthermore you have to click on the bottom-left corner on a little cube and select “Rescan Data Packages”. If everything is correct, the cube should be green. Well, now everything is ready for flashing!
Finally you should make sure that your Lumia is on the homescreen. Now click on “Programming” and select to Refurbish.

Click on “Start” and the flashing should begin. It takes about 10-15 minutes and your device could restart several times during the process. Do not unplug it during flashing!

If the flashing was successful, you should now have a fully working Windows Phone 7.8 device.

This time the Lumia 800 looks somehow old next to the Lumia 610

Something went wrong – What now?

If something went wrong and your Lumia is just a brick, don’t panic there are other solutions. Follow all the instructions from the beginning, but instead of selecting Programming and then Refurbish, you click on “Recovery”. Start it and your device should work properly again. If this wasn’t successful either, download 7.5 from NaviFirm and you Windows Phone should work again.

However, we cannot accept any liability for damage to your device.