I am sorry you are having trouble with your Wixels. I suggest trying a different USB cable and a different USB port on your computer. Since there might be a badly-behaving application on your Wixel, I recommend that you continue testing the Wixels by unplugging them, connecting 3V3 to P2_2, and then plugging them in to USB. This forces the Wixel to go into bootloader mode instead of running the application.
If that does not help, I would like to get more information. Were those two Wixels ever working before? After you unplug the Wixel, connect 3V3 to P2_2, and plug it back into USB, what do you see the red, green, and yellow LEDs doing? Do you see any indication of the Wixels in the Windows Device Manager in the “Pololu USB Devices” category or the “Other devices” category?
Apparently, the USB cable I have been using forever here in my lab was deemed unworthy by both wixels; changing to a different USB cable did the trick!
Now I have to wonder what other mischief this cable has been responsible for, although I swear I have used it lots of times in the last year or so. Are wixels particularly sensitive for some reason?
Anyway, thanks again for the help - I’m up and running now, and have been able to upload and download apps to both my wixels