Ricardo
The first thing that happens when the tray is closed is that the laser turns-on and tries to focus on the CD.
If it is able to focus, the CD spins (given that the motor works!). No focus = no spin.
So Ben is right. Cleaning the lens is always the first and easy step.
The next step may not be so easy.
Replacing the defective laser-ass'y could be next if cleaning doesn't help.
Determining IF the laser-ass'y needs replacement is of course the problem.
Not easy to diagnose remotely
I do have the service-manual for this player. PM me with your e-mail address for more info on that.
rgds,
/tri-comp