How to check for internal damage after a fall?
If your mac is running the most El Capitan (OS X 10.11.x), and was made after 2012, you can perform the Apple Hardware Test (instructions see Method 1). If the mac was made before 2012, or is not running OS X 10.8.4 or above, you will have to follow the second set of instructions I will include in this guide.



Method 1


Disconnect all cables, with exception to the power adapter (which is required to continue), keyboard, mouse, Ethernet cable, and display.
Power off your computer, then power it on using the power button located on the computer. 
Press the 'D' key on the computer while starting up, but before the grey screen appears.
Wait for a minute or two, and select your language.
To perform a quick check, you may press the t button, or return.
To perform a thorough check, you must select "perform extended testing".
The status of the check will appear in the bottom right of the screen.


Method 2


See step one through step 3 in method 1.
Follow onscreen instructions.


Sources: 

https://support.apple.com/kb/PH18765

https://support.apple.com/en-ca/HT201257