I had the same problem as you. But later I solve it my self.
The flexible thin cable that connect to the laser head, a few thin copper wires may broken.
How to check.
You disconnect the flexible thin cable from the laser head. Use a torch light to torch it from the bottom of the cable, and use a magnifiying glass to see it from the top of the cable. You may see a few thin copper wire broken. Usually it is near the laser head cable socket, or at the folded area.
How to repair it.
If the flexible cable broken, try to get a replacement, if you can get it. If you can't, then you have cut it and clean the pvc to have the copper wire to connect it back to the laser head cable socket.
This is how I fix my portable dvd player.
Lee Wah Eng, December 2007
