Just as the title says. I feel like I have tried everything. I am compiling the firmware for Marlin on a Megatronics board from RepRap. That shouldn't be relevant, because I have validated that it is a firmware issue (and not a pin assignment/hardware issue).
When I turn it on, the Y-axis is active and just constantly holding. The stepper driver on Y-axis gets pretty warm constantly holding (as does the stepper motor).
When I swap the pin assignments for Y and X then the physical Y-axis moves fine when I manually change the X-axis so I know all the hardware and pin assignments are correct.
All the endstops are correctly reporting open (Z is BLTouch but that is also working).
Relevant software endstops are currently disabled, and default homing position is set to 50 to make sure it doesn't think it is at the bounds on boot.
I have a test firmware that checks all the endstops, temperature, and servos, and all servos work fine. As a sanity check, pin assignments match what is in the pins file.
Does anyone have any idea of what in the latest Marlin firmware would cause a software condition to just hold the y axis and not move? I should note that when I try to manually move it in Repetier-Host it shows that it is moving. When I try to give the home command, no movement on the Y but Repetier changes from red to black indicating it received confirmation of homing.
I am completely out of ideas at this point.