Is there a way to block the test(s)? I tried the hold-down-buttons power-up. 

That test starts if any button is held down on the H9 when it's powered on.  Could you go through pressing the left and right footswitch, the encoder, and the top row of switches to make sure each isn't stuck in pressed position?  It is possible that one of the switches has failed.  But it's more likely that one of the switches is just stuck.  We've heard about that happening to the encoder about a half dozen times in particular.  (The encoder is the big, black wheel…)