Thank you for the suggestion of Sensor Motion, it is perfect! I found out the only the compass IC gives me an incorrect value. I think this problem is related to the IC which is located near the rear camera FPC connector (right?)
I did some measurements (see picture) but I am not sure which kind of components they are. I have an iPhone 5 schematic but the layout is not the same as this board. (see picture) Does someone have a schematic for this board?
