Last week I hit a tree branch 10-feet off the ground and came down hard. Nothing appeared damaged, but one of the propellers did NOT want to unscrew. I was able to remove it and the rotor still spins but with the SLIGHTEST little hiccup. I fired everything back up and was able to take off. Unfortunately, once I get up about 30 or 50 feet, the lights start blinking red rapidly and if I don't hold UP on the left throttle then it wants to come down. Everything else works well, I can fly smooth and the FPV is working, too (Here's my FPV setup: http://www.phantompilots.com/viewtopic.php?f=31&t=22910#p209934). But after 20-30 seconds following takeoff it wants to come back down. I tried it again yesterday and while it was coming back down by itself, every once in a while it would start blinking green again for 5-10 seconds before switching to the rapid red lights and descending. Any ideas what could be going on?