Homing Z - MakerGear M2 Wtih BLTouch

I’m running Marlin 2.1.2.7 on a RAMBo 1.3L board with a BLTouch.

On a MakerGear M2, when the printer is first powered on, the build plate moves downward, away from the nozzle, before Z homing. However, when the printer is powered off, the build plate is already at its furthest point from the nozzle.

How can this behavior be changed so that during Z homing the bed only moves toward the nozzle?

Is there a firmware setting that prevents the build plate from moving away from the nozzle at startup, or alternatively makes the bed move 15 mm toward the nozzle before homing all axes?

I tried setting #define Z_HOMING_HEIGHT 0, but my understanding is that this only takes effect if Z has already been homed.

Has anyone run into this on a MakerGear M2 or with a similar Marlin/BLTouch setup?

On power up the machine does not know where it is. The only safe move is away from the hotend.

"makes the bed move 15 mm toward the nozzle before homing all axes" and if the machine was already closer than 15mm you have just damaged your print bed and or nozzle