Did I do something wrong?

[miguel11691]

I have installed windows phone 10 on my Lumia 640 and it installed after about an hour or so... Never had that happened... When I chose to reset device so I can have a fresh 10166 it completely licked up and just kept boot looping...

 

[xandros9]

I don't think you did anything wrong, I think you just ran into some bad luck. If its unusable, I'd hook it up to the WP Recovery Tool and restore it. After that, upgrading to 10 shouldn't run into issues.