If the user gets this error, they can attempt to remove the cutter manually by going to the tool change menu and pressing "force release".   

If the cutter still will not release from the collet, then the user can perform an emergency release.  To do this, power cycle the mill by turning it off and then back on or pressing the e-stop and then resetting the e-stop.  This brings you to a screen that looks like this:

DO NOT press enter.  Instead, look to the button panel on the right and press spindle:

You will then see a screen asking if you want to perform an emergency release.  Press Enter.  Carefully (the cutters are sharp, use gloves if you need to) pull the cutter from the spindle.  Check the tool and the collet for any debris and clean as necessary.  Perform several tool changes to confirm proper function.