Without more details (like seeing some code).
1) Do not block the UI thread, this can cause a SIGABRT as the OS will kill a non-responsive app.
bind and unbind on every activity when i switch for like 11 times it crashes my app
2) Make sure that in your OnDestroy within your Activity you are cleaning up after yourself. i.e. Removing all your Listeners/Events and then calling the Base.OnDestory.
3) An external (i.e. BluetoothLeService) service calling back into your app with listeners that now null/nil will cause hangs and thus a SIGABRT, see #2