Here's the link to my latest video, showing how the scope can actually _start up_ in the frozen state, after being shut down while running perfectly normally.
The easiest way to reproduce this is probably like this:
Disconnect all the probes. Go to Storage>Default (press button) and the scope will reset to most all defaults, with CH1 turned on. Verify that it is at 1.00 us/div.
Now turn on all the other channels. The traces will overlay in the center of the screen, that's OK.
Set Utility>System>Power Set = Last.
Set Display>Persis Time = 100 ms.
Set Acquire>Mem Depth = 6M (or highest available).
Now enter Horizontal Zoom by pressing the Horizontal Scale knob. Everything still works, right? Not frozen, because you have 6M set instead of Auto in Mem Depth. Fine.
Now _exit_ horizontal zoom, and cycle the power. When the scope boots up, see if the Acquire>Mem Depth has changed to Auto. If it has... then you've got that little bug too.
So change it back to 6M.
Now enter Horizontal Zoom mode. Everything still works, right? Not frozen.....
Now cycle the power again, while still in Horizontal Zoom. If you've got the bug like I do, the scope will start up _in the frozen state_ and you can't even do anything about it. This happens because the Mem Depth has forgotten you set it to 6M and has reset itself to Auto, hence fulfilling all the conditions for lock-up.
Congratulations... you may think you have now just bricked your scope. Fortunately it will come back to life with the "5th button" procedure.