The fact that it did home may mean an intermittent issue. MAYBE. 760-16 or 760-22?
Reason being the maintenance page. If you can get into it and in the left window bring up following error for X, Y and Z and monitor it in greater detail . You can actually see the positioning error on the right side of the page where it shows position and the error. With the drives off, grab the X and the Y ball screw and turn each. Does the machine count (change position value)? If you home it watch the position error for each axis and see which one is the offending axis.
It will probably be the encoder or the cable. Outside chance, the BMDC. I just had to replace a X axis encoder cable on a VMC1000. It moves in the plastic flexible wireway exposed to oil and coolant and eventually become hard and brittle. Th outside cracks, then wire flexes more where it is cracked and work hardens and breaks. You would be quite surprised the difference in flexibility where it is protected and where it is exposed.
Also if you try turning the X ballscrew by had and you have a lot of difficulty, it might be that the keeper plates became tight. I have had about half a dozen machine do this in the last 15 years. The fix is to rescrape the turcite on the keeper plates or use about a .001 shim to space them out. It cause the motor to run hot and melts the wires in the heidenhain encoder causing a short. Had to mention this because I have seen it more than once.