U2413, capacitive touch buttons not responding

The monitor is only three months old, and I've probably pressed the buttons less than 20 times. I went to change inputs today, and the buttons do not work at all. The last time I tried would have been sometime in mid-December. I power cycled the monitor, and they don't light up on power up like they used to. I guess I just didn't notice that change and couldn't say when it happened. I unplugged the power for about 5 minutes, and that didn't help either. I removed all cables except power and got the floating box for unconnected display, but the diagnostics key combination did not work. On the mini-displayport input that it has been set to, the picture is fine and looks great, but it is not useful to me if I can't switch inputs.

Any other ideas on getting these to work again? It seems weird that all five buttons would just stop working all at the same time. There is nothing that should have caused it. I haven't even so much as wiped the dust off the thing since I got it (to my chagrin when I was trying in vain to find a service tag number). The power button is fine, but it is a real button instead of a touch sensitive disaster.

How reliable are these touch sensitive buttons? My older Dell Ultrasharp with real physical buttons is still working great after 5+ years. I really expected more out of the Ultrasharp line. I may just get rid of it once I get it replaced if they are problematic, if I can't convince them to refund instead of replace. The Dell tech support experience I had today was so beyond awful and useless that I don't want to keep it if I have to deal with them ever again. I REALLY wish I hadn't filled out the survey I got this morning with positive results. I still have to call some other random number that is not open on Sunday to try to get the replacement started.