I'm in the process of replacing the laser on this unit myself, and according to the sony service manual for this product, on one of the boards on the laser unit, there should be two fairly large solder points between the two ribbon cables on the board. The blueprint has the solder point location labeled as "SL001," but i have not confirmed this label on my unit yet. According to the manual, when you solder those two points together, it protects the board from ESD (electro-static discharge). The manual recommends soldering those two points together during service. Then, after servicing, but prior to testing, you MUST remove the solder from those points. Failure to do so may (probably will) result in inoperation of the unit.

Had I not just read that part in the service manual, i wouldve been confused by that instruction too.

I hope this helps. PM me your email if you'd like me to send you a screenshot of the section of the service manual that shows this. It might help with the location of the two solder points on the board.