I am using Lumia 520 with "cyan", One day suddenly my phone got stuck in flight mode and it never set right. When i asked the service centre guys, They told me some bullshit and demanded 4600/- INR. I searched on the web also, couldn't find any possible solution. But somewhere i have seen a comment which says, it worked with "Lumia software recovery tool". I just wanted to try it as a last hope.
And Finally it Worked out....!!! :)
Just wanted to share it with al of you. Hope it works for you as well :)
Steps to follow:
A big hassle here is that the download size pretty big and the max speed would be around 200 kb, even though you use high speed internet connection.