For those who are having upgrade problems.
These may seem like a lot of steps but they are probably the shortest reliable path if you follow them all. Not all steps are needed by everyone, but every step is needed by someone out there and you can’t really guess which are which for a given system.
[Edit: Older, smaller USB sticks seem to be working better for people: formatted as FAT or FAT16, tho FAT32 works sometimes it’s dependent on where the files land on the USB stick. There are some recommendations below for USB thumb drives that worked for people.]
As was mentioned disconnect any non PS Audio I2S sources.
If (since the last time you formatted the USB stick) you EVER took the USB stick out of a computer without using the OS’s eject function, format the USB stick (really.)
Make sure the new files are in the root of the USB stick. If you are paranoid make sure nothing else is in the root, but this isn’t really necessary.
Turn the DSJ off for a little (let the power supplies bleed down), say 10 or 20 seconds.
Put the USB stick in and then power on the Jr.
The Blue light will blink for what seems to be an eternity.
After the system boots up, remove the USB stick and turn the Jr off again, wait, say 10 seconds and then turn it on again.
If when the system comes up the version numbers aren’t that of Snowmass then do all of the above with an OS that is different than whatever your were running yesterday (Yale is popular tho Huron, Torreys, are also fine, just not the one you were upgrading from.)
Then do it again with Snowmass.
If you are still having problems you might check if you followed ALL of the above for going to, say, Yale and then all of the above to Snowmass. If so contact PS Audio support (or read a lot of this thread for inspiration or as a distraction 
)