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.