So, let me show you guys my solution.
I have a xiaomi redmi note 3 and had the pebble classic kickstarter edition. It worked perfectly fine until a week a go. So i decided to buy the pebble 2. And so, the problems begun. It didnt worked at all, i did everything, reinstalled it, used gadgetbridge and so on. So i tried to pair it with an old Iphone (4s) with the pebble app and the watch worked perfectly. The watch upgraded the newest firmware. After that i diconetcted it from the Iphone and tried to pair it with the android app on my xiaomi.
At first i didnt worked, so i tried gadgetbridge again and it finnaly worked. But i still wanted to use it on the pebble app and tried it again on it, and thank good, it works now.
I hope it still does after that.
Just dont surrender, try evertyhing u can. It´s a very nice watch.