If you have time, remember to go to a friend’s computer and try to flash with it. Also try a different USB cable. Sometimes even changing to a different USB port (back vs. front or add a powered USB hub). These are all things one can try while waiting for a recommendation from @svetlana.nikolenko.
This was a long time ago I even put an RS in the freezer for 30 minutes and I was able to get a successful flash. I don’t want to really suggest that putting in a freezer is the right thing to do because we might start another “cargo cult”, but when there is difficulty flashing any device (whether Reach or other type of hardware) sometimes a small change can bring success after lots of failures.
After all, we just need all the digibits to get put in the right place within the eMMC chip.
(check the MD5 sum of your downloaded image too: http://files.emlid.com/images/reachview-MD5SUMS to make sure your image file is not corrupt)