The reason why I disassembled my presenter was, that the laser diode (red) did not project out of the case any more. You can clearly see the laser being at a very odd angle. I can not imagine how that happened.

The yellow marker shows the battery connectors you are not supposed to break in step 4.

In the last image you see the "fixed" laser diode. I just gently pushed it down, now it's working again.