You can only unlock the panel with push buttons by performing a factory default:
Hold DOWN button and press MODE button twice - page 35 of XR Manual from June 2018
Take care, this makes a factory default and all paremeters changed from default will need restoring.
Otherwise via an ASCII command J=U
Or XF (factory default)
Also in DTMD 5.4.1 you must close the software before disconnecting the sensor as the software unlocks the panel.