One reason is if he joystick is deflected by something pushing on it when the pendant boots it sees this and disables the joystick.
Did you make sure that joystick lock is off?
There is a way to force the pendant to recalibrate (it first does the touch screen and then the joystick).
But this requires connecting to the console port (which on the current main computer is not installed as standard - but you will have it if you have a fieldbus adapter), and then typing in a command to the base OS.
Do you have a local ABB office that could help you with this?
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