The USB port in the armrest compartment is not working.
Having a failing or non-working USB port in your Infinity is actually a problem I have seen in many vehicles throughout my years. In most of those cases what I recommend first is plugging in a different USB cord and also ensuring that the device plugged in has fully updated software. This usually resolves the matter without need of any major repair. If after trying these options your Infinity is still experiencing problems with its’ arm rest USB port, then the next possibility is that the USB module is failing or there is perhaps a wiring problem. At this point I would highly recommend enlisting the assistance of a certified mechanic who can perform electrical testing and get your Infinity’s USB port back to working order.