@ubuntu_guy
Well, your problem sounds the same like I had with my M10 FHD.
I got a workaround from Marius Gripsgard.
I wrote here, how I did it:
https://forums.ubports.com/topic/263/can-t-get-the-m10-fhd-to-take-the-flash/3
Some people saying, that my hardware is damaged, but how come, that so many peoples hardware is damaged the same?
Just leave a comment below my howto, if this was successful for you. So I can see, how many people encounter the same problem. Thanks.. 🙂

On my device, I have the problem, that the WiFi password will not be stored. I have to reenter it every time I reboot and connecting to the same router. I am not sure, if this comes together with that issue. What is your experience?