I encountered the same problem. The devices (all RUTX09) belong to batch 16 and 17 but I don't think this is significant. I tried to update the firmware but without success (tested versions: RUTX_R_00.02.06.1, RUTX_R_00.02.05.2 and RUTX_R_00.02.03.4). I have noticed that the blockage occurs systematically if the device is disconnected and re-powered in a short interval of time. If the device is disconnected and kept off for 15s or more, the next time it is re-powered the boots sequence is completed correctly.
Do you plan to release a fox for this problem?