I have the Phantom 3 Pro, bought back in Feburary. I have had everything packed away in the backpack for a couple weeks and I got a new phone so I was checking to make sure it worked with the DJI Go app. The battery was dead so I plugged it in. Nothing, no lights just nothing. The drone battery charged just fine though. It wont even power on when plugged in. Any suggestions?

On the pro you want to make sure that you are not trying to charge the battery and the controller at the same time.  I thought mine was dead because I put it away for a couple months, yet it turned out that I forgot how to turn it on properly.

Please keep charging it for one hour, if it is still no lights, you may need to send it in for service. https://repair.dji.com/en/SelfRepair/Area

DJI Diana Posted at 2017-6-26 00:49
Please keep charging it for one hour, if it is still no lights, you may need to send it in for service. https://repair.dji.com/en/SelfRepair/Area

That's good advice.  If the battery is really low, it may not show any sign of charging for the first while.