Identifying whether display is broken or the motherboard
You can use ADB to test phone functionality. ADB tool can be obtained from Android SDK. There are a number of test commands which you can use to test your phone. Steps are as follows:


cd to your ADB directory.
Connect your phone to PC via USB.
type the following command:

'adb devices' (without quotes)


You should see your android listed in the CLI. You can also enter device shell:

'adb shell' (without quotes)


List SD card contents:

'ls -l' (regular unix file navigation commands)


If you can access your device shell, it's most likely that your motherboard is working fine. There are several commands to check as well:

Sending user touch events to Android:
adb shell input keyevent &lt;event_code&gt;
1 --&gt;  "KEYCODE_MENU" 
2 --&gt;  "KEYCODE_SOFT_RIGHT" 
3 --&gt;  "KEYCODE_HOME" 
4 --&gt;  "KEYCODE_BACK" 
5 --&gt;  "KEYCODE_CALL" 
6 --&gt;  "KEYCODE_ENDCALL" 
7 --&gt;  "KEYCODE_0" 
8 --&gt;  "KEYCODE_1" 
9 --&gt;  "KEYCODE_2" 
10 --&gt;  "KEYCODE_3" 
11 --&gt;  "KEYCODE_4" ..... etc