See its a long time ago you had this issue. You can try to remove the cable from front camera/sensor/earpiece from the motherboard port and gently push it back on. All the problems you relate to is thru the same cable. If this dont solve your problem, check if the earpiece is correctly placed onto the polarity poles, and that the proximity sensor is lying right down into the corresponding socket. If something is blocking the sensor, yeah then the screen wont turn on/off when you put it onto your ear.
Some here states they are hard to remove. I used one of my Philips screw drivers. I'm not sure what type, but it removed the two screws easily. In the years that have past, doing repairs, I have got a lot of different equipments. Just be sure to use exatly the right screwdriver.
I'm a little bit suprised by the comments here on this step. I used a hairdriver, and a sharp scalpel. With extreme caution I got it off in 1 minute. And its in perfect condition. I guess the adhesive may be stronger on some than others. I started on the right by the right pole, and worked my way to the left. Remember to warm it up enough, so that the adhesive is weakened. Waiting to long just make it strong again.
