same problem here... trying to update from 2.1.5 to 2.1.7
i used the same stick (SanDisk Cruzer Blade 32GB) to Update to 2.1.5 - this worked fine
i removed the old vuplus folder in the stick and extracted the 2.1.7 zip provided here for the solo2
all steps during update seem to work just fine (front usb) - but in the end, it just boots into 2.1.5, which you can tell immediately by still using the bright blue bootlogo... and is confirmed when entering the menu/information/about settings... still says 2.1.5
i don't know where to go from here :/
i tried another (older stick) - same thing....