Setting defaults lets you open XY window, no problem, but I think I powered down the 'scope yesterday when it was in XY mode and today it won't boot up any more. The 'scope app crashes on startup.
My scope had the same failure to boot, but after using the feature to load the previously used setup on booting. I unplugged all of the cables overnight, and it booted the next day. And, yes- I do regret buying this scope. And, no- RIGOL doesn't seem to care.