Hello!
Just got the CM3+, installed it in my Slice, plugged it in and nothing.
Using the power supply that originally came with the Slice.
Using USB port connected to my laptop running Ubuntu I can see my hard drive and write to it, but I am not seeing the eMMC storage on the CM3+.
Put the old CM3 back in, works, updated to version 9 (I've not used this for quite some time since it was replaced with a NUC).
Back to the CM+ and no go. Any suggestions? Tips?
Thanks in advance!
Update:
Figured it out. I did this thing called "reading the directions". 
Started here:
Flashing the Compute Module eMMC - Raspberry Pi Documentation
Followed instructions for Linux. Connected USB first, then power cable to get the internal storage to appear.
Then to here:
Installation of LibreELEC [LibreELEC.wiki]
Again, followed the Linux instructions.
Unplugged everything, connected to TV and powered up. Everything came up normally.
Hope this helps someone else that gets stuck after so long without touching the thing.
Added it to my home Wiki so I can reference it in the future :).