When I plug in a DT402D throttle to LocoNet using a DCS240 as my Command Station, it flashes the display as normal then fades and continues to reset.
Make sure you have a charged battery installed in your DT402D. The DT402D is attempting to power on the RF24 radio in the throttle and register with the UR92. Without a battery it cannot draw enough power from LocoNet to complete this procedure.
If you plan to use your DT402D as a tethered throttle it is recommended that you use throttle options to turn off the throttles duplex radio capabilities. Press OPTN and scroll to “DuplexRF”, change to OFF with the N/- key, press ENTER to save the setting.
It should also be noted that this problem will only occur when a UR92 is connected to LocoNet. If no UR92 is connected the DT402D will connect to LocoNet as a tethered throttle without a battery.