Yes I do confirm that I've had this bug on CX even without using Ndless.
Removing the battery was the only way for me to skip the "gray" screen.
So it's a bug.

Which means the warranty should cover it? (I'm guessing installing Ndless makes the warranty invalid. But after the complete format there shouldn't be any trace of Ndless..)
Or is it idiot proof to unplug and replug the battery?