The v90 ships with XPe on it.
You can install different operating systems on them, but it’s not really “supported”. When you think about it, these thin clients are really just “low end” computers.
There are two ways you can get that machine back to factory defaults. The first thing I would look at is imaging with a USB memory key. Follow that link to the download page and you should be able to follow along and get it working. It’s pretty straight forward.
The other method would be to use the Wyse Simple Imager. This method will let you use a network cable to PXE boot the v90 and load the firmware back onto it.
Either way, you’re going to need a copy of the firmware. You can find it here.
Good luck!