Image flashing online issues

I am posting in the Duo2 section but the same symptoms happen on a Uno4K both with open atv images so it may be limited to those images I don't know.
Does anyone use the online flash facility? if so have you tried it with ATV 6.2 or 6.3? I found that the boxes will download the required image then go through all the motions of correctly installing it only to reboot to the old one.
I had to resort to using a usb stick to update the Uno, and before anyone asks why I don't do that to the Duo2 as well the answer is that the box is miles away from me so it needs to be done remotely.
More confusing still (for me) is that I found that a restore from a full back can be done successfully using the same online flash but this time selecting the old image instead of the downloaded new one. Any ideas?

Sounds like you have a vuplus folder containing your last backup on your usb stick, just rename it and try again

Didn't think of that, I will give it another try, thanks.

Edit just to confirm that it worked, still tricky to get into the box from outside the lan as webif access is restricted as a security measure so lots more fiddling adding lines to settings and using putty ssh etc