I had a similar issue with not being able to move Z axis to home. I kept hitting a soft overtravel limit before I could get the machine to find the home point. My machine is a different build though: Conquest T42 w' 18T controller.
Anyways, both travels need to be manually jog moved 1" negative X and negative Z before you can go towards home. If you're too close to they physical limits before crashing, you may have to manually move the turret with some leverage to push the turret to provide clearance for your 1" move before zeroing. It seems to be a goofy error mode to have having to pry your turret around with the machine depowered but that was how I got to a position where I could move the Z towards home before triggering a soft limit.
Have you tried holding reset while pushing +X or +Z? IRC that should override an inhibit which should allow you to move before homing.