Hello,
How was the factory reset performed? Did it really reset?
Have you tried not the default password, but the password, used before reset?
Did you attempt to access the device via SSH?
Did you try holding the reset button for 12 to 20 seconds to reset to defaults?
As suggested above, could you try performing firmware update following bootloader recovery instructions here? Try installing RUTX_R_00.07.02.8 firmware. Then check, if default password written on your device works.
Could you send the device's serial in a private message?
Best regards,