This should be simple. Press down on the LCD on the right side of the phone. If the phone feels like it has a soft area, the phone needs to be taken apart for inspection. Phones that do not have a bulge on the battery side of the phone are probably fine. However, it may still be a good idea to open the phone to be sure.

Do not use too much pressure for this. Using too much pressure can damage the LCD. If you break the display, it usually ends up costing more then a replacement display. Breaking it is basically a death sentence to the phone.