Mars 2 Pro - unable to level or set Z=0, loud humm

[pouncingdragon]

I just received a Mars 2 Pro, and am having issues with the setup.  After removing the resin tank and placing a piece of paper on the deck, I loosened the screws securing the build platform, went to Tools -> Manual -> Home per instructions.  The deck slowly lowers until it is pressing on the paper, then begins to make a loud humm and vibrate like it is trying to push the platform down further.  From a bit of research, it looks like it is supposed to press down and then lift back up.  I can hit Stop to stop the noise and manually raise the platform until I can pull out the paper (with resistance), select "Set Z=0" from the main menu, but am given a message saying "Home first, then manually adjust Z-axis to the best position".  This appears to be different than the confirmation box I see other people getting.  I am on firmware V4.3.13_LCDC /1620x2560 /F2.23

Anyone have any suggestions for what I might be doing wrong?  I appreciate any help!