I have a ver4 no solder mod PS2. It has worked fine for a long time. A couple weeks ago it stopped playing dvd games and movies (originals and backups). It would still play PSX and PS2 blue bottoms (backups too). I replaced the laser and the same thing is still happening. Does anyone know what's up with my PS2??? Thanks.

Sounds like you got a defective replacement laser.

best to email the place where you got the replacement laser from to get an exchange

Yes, they are right.....Definately the laser. There is NO internal hardware, or device OTHER THAN the laser that can cause this behavior. Get an exchange and you should be happy.
Besides, we have seen this exact same problem many, many times.