Is there any way of calibrating the inbuilt accelerometer? I have the artificial horizon displayed when taking photographs but unfortunately the phone needs to be reading 4 degrees before the grid lines align with the horizon (which in my case was the distant sea). At this moment the centre line in the target appears indicating that the phone feels it is horizontal, when clearly it isn't). I've tried calibration apps where you place the phone on a flat surface but this makes no difference. I'm just wondering if I have a phone with faulty hardware and need to send it back.