You might have heated it too much so it destroyed the touch sensitive parts of the LCD screen. Do you have the old screen you can put back in to test it and see if it works? If it still works, then it's the new screen that needs to be replaced again.
After doing some research, I found this. When you start your PS3 be sure that the blue light is lighting up. If it's not, then is a BluRay reader problem and maybe you should double check the ribbon cable connection.