Your phone might not to turn on after repeatedly pressing the turn on button. Some possible explanations are detailed below.
If your phone won't turn on and the battery does not hold a charge, then the battery is dead and needs to be replaced.
It is possible that it appears nothing is happening because the display is bad. The screen might have taken in water or it might be cracked. If the display is faulty, it must be replaced. Here is a link to replacing the LCD screen. Motorola Defy LCD Replacement
If all of the other has been checked, the problem most likely lies in the motherboard and must be replaced. If your phone has been in contact with water it means that your motherboard might be damaged. Here is a link to replacing the motherboard. Motorola Defy Motherboard Replacement
You have tried to turn the volume up and down, but cannot hear anything.
Before tearing the phone apart, check to see that the volume on the phone has not been muted.
If you have checked the phone to make sure the volume is not muted and there is still no sound, then the speaker may be broken and must be replaced. Here is a link to replacing the speaker. Motorola Defy Earpiece Speaker Replacement
You know a friend is calling you but you are unable to establish a connection.
If calls are not connecting or being dropped, this may be due to being in a poor area for cell phone reception or signal. Often times, one can check the cell phone providers website and see a map of good and bad cell phone reception areas.
If, after checking the cell phone services map for good and bad reception areas and the signal and phone calls are still not connecting properly, then the antenna may be broken, and must be replaced. Here is a link to replacing the antenna. Motorola Defy Antenna Replacement
You have tried to use the camera on your phone, but the camera does not seem to be working right.
Before taking apart the phone, make sure that the phones screen is working properly. If you cannot do or see anything on the screen, then the LCD screen is broken and must be replaced.
If you have checked the above for any errors with the LCD screen, and everything else seems to be working properly with the phone, then it is most likely the camera module itself is broken and must be replaced. Here is a guide to replacing the camera module. Motorola Defy Rear Facing Camera Replacement