According to your descriptions (item 2,4,5), learning that put the pan & tilt PCB of the unit serial no 8120130300393(No.49) into the unit serial no 8120130300414(No.70), it can be controlled normally; and put the pan & tilt PCB of the unit serial no 8120130300414(No.70) into the unit serial no 8120130300393(No.49), it can be controlled normally. But it’s very weird that put the pan & tilt PCB of the unit serial no 8120130300393(No.49) back to the unit serial no 8120130300393(No.49), it can’t be controlled. That’s almost impossible in my understanding, unless it has a poor connection.
Could you please send me all the PCBs(Display control PCB, Pan & tilt drive PCB, LED drive PCB) pictures of No.49 and No.70 for reference?