I have Nokia Lumia 620 and installed the windows insider and it wont download any updates via internet. So I thought roll back to windows 8.1
The problem is it needs to download 1.5 gb and I have 512 kbps internet.
So I used fiddler and downloaded the 1.5gb file using download manager. It's some "signed.ffu" file.
Now the problem how to use that ffu file to install in windows phone.?