If it works by unplugging/re-plugging the cable, I wouldn't suspect the RR2160's USB port. That would seem like it's putting out the 5 volts. I would suspect the USB cable or the 4 pins being oxidized, either on the cable or the port.
Try plugging in and out several times and leave it plugged in. That will scrape the pin contacts together and remove any surface oxidation.
Then turn the RR2160 off and back on and see if they power up together.