So the spindle is stuck while tool changing. Most likely you've incorrectly loaded the tool into the fork ABOVE where it should be. Hopefully, it just errored out on the Z-axis. You can easily correct this, thankfully.
- M11C1, Enter.
- Hit Home button it will leave the jaws open (and lots of air will continue to flow out).
- Once it has homed, type in M12C1 to close the spindle jaws.
- Then use L110 T0 to make sure it has no tool in the controller.
- Fix the tool in the fork and make sure all the rest are correctly loaded (see image).
- You are ready to run like normal.
We found the safest way to not have it stuck in a loop is to just home the machine.