public void selfTest(){
  checkConnection();
  final List<BLEAction> list=new ArrayList<>();
  list.add(new WriteAction(Profile.UUID_CHAR_TEST,Protocol.SELF_TEST));
  queue(list);
}

public void selfTest ( ) { checkConnection ( ) ; final List < BLEAction > list = new ArrayList < > ( ) ; list . add ( new WriteAction ( Profile . UUID_CHAR_TEST , Protocol . SELF_TEST ) ) ; queue ( list ) ; }
your mi band will do crazy things ( led flashing , vibrate ) . note : this will remove bonding information on the mi band , which might confused android . so before you connect next time remove your mi band via settings , bluetooth .
