Problem after installing new Lens for LG DVD Player !!
I've been working on DVD players since they were invented, and was factory trained by Sony, Hitachi, and Kenwood, but I must admit, I'm not understanding your question.
The laser diode fires through a lense, that is supended on tiny wires, and moved into focus by an electro-magnet. Now, I have replaced lenses that have popped off due to poor adhesive from the factory, but I have no idea what you mean by "unlocking the lense"
If you mean that you have replaced the entire laser ***'y, and it is not emitting, then that is likely because the shorting bar has not been removed. It protects the laser during shipping and storage, and must be removed. If you compare it to the old laser, you will see pins shorted together by a tiny metal bar, or in some cases just solder...if this is not removed, the laser will not emitt. If you put the old one in and it does, then 99% that is the problem...if the old one does not, then the laser is probably not your problem. Hope this helps, and be careful to always look at the laser at an angle to check for red light, so you aren't performing home laser eye surgery...not a good idea!
P.S. After re-reading your question, on some models, it is possible to replace the lense ***'y, because the electro-magnet has failed in some way, and does not move the lense, but if that is the case, I don't know why the laser would suddenly stop emitting, just because that was changed...normally it is all one ***'y. Good Luck!