Upgrade to FW 8.0 then router failed to write configuration data to the flash memory

I have a new 20X running 8.0.2 out of the box. It let me set up the unit, and a couple of days after being on-line, I made a small change and got the “failed to write flash” error. Tech Support has had two remote support session with my modem along with associated reboots. Still getting failed to write error. So far no solution from tech support.