I just reset my lumia 640 xl and while processing it is showing this symbol

[Windows Central Question]

I'm having windows 10 developer's version in my phone so I reset it and it is having trouble. I'm just not able to turn it on. It is showing reset process, process completes and then it show symbol ":-(" and again shut's down

 

[eusty]

You will probably have to reflash it with the firmware recovery tool as something must have screwed up with the update.