Issue ThinOS 8.6 to 9.0 upgrade

Hello people,

I have a problem with the direct upgrade to 9.0.1136. I updated my WMS to 2.0 and tried the update this way:

https://www.youtube.com/watch?v=PXvZN9aWLEI&feature=youtu.be

I'am trying to update our Wyse 3040 terminals from 8.6 (tried 206 or 303). After preparing the update the client restarts and that's it:

I waited few hours but nothing. Also few power off an on did not solve it. The only way to fix a wyse client from this is to boot from USB and install a merlin image.. 

Any suggestion?