It's.. really unlikely to happen. Is it really running normally when in debugger and in .exe? Have you tried using the adb logcat to see what actually happens before your phone "bricked"? There may be some clues found from it.
It may also be because your Godot version. I don't know about Godot 3.1, but for Godot 3.0, it doesn't do well in Android field afaik. I've ever tried exporting to Android in Godot 3.0.x and my game became mess just because I enabled