If you are having problems with your Mac's hardware and nothing you can do on the software side can fix it, then follow these steps to reset your Mac's PRAM and NVRAM.
Step 1) Shutdown the computer and unplug its power cord.
Step 2) Hold down the CMD-Option-P-R set of keys all at once and turn on your computer.
Step 3) Wait until the computer restarts and you hear the startup noise a second time (usually at full volume).
Step 4) Let go of the keys that you were holding, you have now successfully reset your PRAM and NVRAM!
If you have any questions about this process, please feel free to leave a comment!