Xperia Z2 :: Why Phone Continuously Vibrating

This is the second issue I have had with my Z2 since getting it in May, the first issue was a self cracking back that Sony at first refused to repair under warranty, eventually they did. 
 
Now, after finally deciding to use the phones waterproof feature today I am having another issue. I submersed the phone in my backyard pool (no chlorine) and recorded a snapchat message for about 10 seconds. I pulled it out, dried it off and carried on. I then went to take a photo normally about an hour later and I noticed a ton of vapour or condensation on the inside of the camera lens, great. Then about an hour and a half after that, the phone started vibrating and has not stopped since. It's been about 2 hours. It stops everynow and again for a few seconds, then it just goes off it charts again, and it is so annoying. 
 
Yes, I turned it on and off, it just continues to vibrate. I tried to hard reset it, pushed the red button down, it just turns off, doesn't actually restart. Of course all the covers were sealed, I'm not stupid, I look after my electronics.