Does anyone know how to troubleshoot these wall outlets? Both USB ports are dead however the wall outlet port works just fine. Prior to this I was able to successfully charge from USB port for about a week, and there has been no change in wiring. Is there a fuse ? Tendency to overheat?
Unfortunately these USB sockets fail regularly. We constantly seem to be replacing them. The irritating thing is that the failures aren't all from crap brands. Market leading brands like MK and Legrand fail just as much as the cheap China knock offs. I have never seen any of these sockets to be fused before, but clearly they are overloading. iPads and other tablets seem to be the largest culprit as they draw way more than standard current. However, it's a disappointment from the mainstream brands that they do not have a self resetting overload function or at a basic level a simple fuse. Crazy how smaller electronics companies can make robust chargers yet they can't.
As for diagnosing. There really isn't anything to diagnose unless you try a different cable and device to check for charging. Normally it will require replacement. I would ask though what are you charging in this device? And secondly do you have the socket part number as the socket will have a data sheet with its maximum rated current for the USB socket part.
Depending upon the manufacturer there may very well be a huge range of quality related to the reliability of the USB charger portion of the outlet unit.
Just think about that basket of multi-colored cheap plug-in USB chargers near the checkout at the retail store. Almost certain to be the lowest tier of quality.
So consider evaluating your unit relative price and reliability. Maybe the simplest thing is an upgrade or replacement.