Maybe not. Your battery ought to be dead by the time you retrieve it, but if it is still blinking, turn if off immediately. Then take everything apart, dry everything carefully with compressed air, and then and bury everything you can with loads of rice in some tupperware closed tight. Do not even think to go flying earlier than a week after you have put it in there, and even then I would be extremely cautious because there is no telling what the Phantom will do after getting wet. It is very difficult to tell what may be fried or shorted. Be careful when you remove the top, because the GPS cable connects the top with the bottom. Be sure to use the right screw driver for the right screws so that you don't strip the screws, and be sure to put the top back on in the same orientation as it is now. Some guys have messed up by rotating the top 90° relative to the bottom. Good luck. Let all of know how it turns out.
Where are you located to be so lucky to have 3 hours of rain?