Pioneer PDR-05 issue, won't recognize discs.

I got this unit a few days ago but its not working. The lens of the laser unit fell down. I glued it back carefully, and when i put in a disc, close the door in the display appear: CD-R, CD-RW and in a few second CHECK DISC. The error code is P6. The motor spin up the disc, the laser is trying to focus but after a few seconds the disc stops. Someone knows a solution or typical failures?
Thanks.