Flashing with RF Connect

[ITCactus]

I cannot flash 1.9.0. it stops at 13%  I tried 1.8.0 and got the same results.  Is this due to recent updates to RF Connect?

it could be you experience this issue... 
if it's on android, try Gadgetbridge app (or Siglo on linux),

and like JF002 suggested, 

So, as other said, reboot your watch between every attempts, try with another phone/computer and another companion app and, if possible, analyze and debug to find out why the transfer failed and how we could improve the code ;-)

Also, note that most of the companion app will only accept the DFU (.zip) file, while Amazfish only supports the image (.bin) file.