I plugged it in and the light bar won't light up. The battery icon on the screen has a question mark on it as well. I tried resetting it too but that didn't work. Has this ever happened to anyone else?

If this happens, it most often seems to be the usb cable that's at fault. Try a different one if you have it, or a different controller. Either one of these troubleshooting methods will confirm it.

Has it fallen from your lap/hands? maybe the battery disconnected internally. If thats the case, you would have to pop it open... Or maybe the battery fried. You need to be sure in order to get a new battery, and replace the one faulty

use the default usb charging cable

If you see a ? on the console to the controller that means that the system isn't able to get info from the controller through the cable you're using, it is likely to have been damaged, either swap out the cable for the original or if it is the original try a different cable, any android phone charger will do the job.

I'm really surprised by how crappy the DS4 battery is, in terms of playtime per charge. I'm also not a fan of the placement of whatever you call those buttons that are immediately next to the touchpad. The DS4 is really the only thing I dislike about the PS4. But, I really dislike it, relative to the DS3 and the XB1 controller.

As for the problem you're describing, something similar (but not exactly the same) happened to me a couple of times, over a couple of days. The controller would not take a charge, but it would work when plugged in. The problem seemed to fix itself both times it happened, within a matter of 12-24 hours.

Sucks the battery is internal and not as easily replaceable as Xbone's.  I used to laugh at the backwards tech, but now I don't.

This thread brings me to the question: Is it only me or does the DS4 tend to destroy USB cables? I swear to god that sucker destroyed a dozen of my cables. I'm still not quite sure why it happens, ut everytime I use a cable with it, it breaks down after 4 weeks or something. I had the idea that it's because of the placement of the port and that I shouldn't lay it on the back while charging. So I always lay it on the analog sticks since then, but the cables still get destroyed. It also doesn't matter if I use cheap cables or expensive ones. That thing destroyed even my Xbox USB cable, the one with this neat little light that shows when my Xbox Controller is fully charged.

I experienced such problems with four different DS4. One from the very beginning at launch, one from a friend, one I bought new and the one that came with the Pro, the new one with the light bar in the front. So do I have incredibly bad luck or have some other folks here experienced similar things?

I'm still using the original cable that came with the PS4 so probably just you.

Nope, it has never been dropped. I'm starting to think the battery might be lose inside somehow. Can I just unscrew it or something?

Thats exactly whats happening here except it won't fix itself.

Now, that is crazy. I can empathize to some degree though.. I had 3 XB360 controllers in a row suffer from controller drift on the right analog stick. It drove me nuts. As far as the DS4 goes, no problems with cables, or anything else.