Hi guys, This is my first time posting, but I've ran into an issue with my Macbook Pro that I really want resolved, so figured this would be the place to ask. A little over a month ago, out of nowhere, my Macbook would not boot up. Whenever I tried booting it, a folder with a question mark would appear. I did some online research and decided to bring it into the apple store at my college. They sent it in to Apple and they replaced my battery, I/O board, the SSD connecting cable and the fans. Upon receiving my repaired computer, everything worked great. My computer would boot properly and everything. That was until about a week ago. While in one of my lectures in class, I noticed my computer was off even though I never powered it down. I tried booting it up, and my computer ran into the same problem as before. When I tried booting it, a folder with a question mark appeared. When I brought it home later that day, it still wouldn't boot. But then the next day at school, I tried booting it up again and it booted perfectly normal. Then later that same day, it turned itself off and wouldn't boot. I've been running into this issue for about the past week. It will boot up sometimes, but then it will power itself down and not boot up properly. I've noticed that sometimes when I gently shake my device when it is not powering up correctly, it will boot up. I also receive various images when my computer is not booting properly. When it is not plugged into a power source, a folder with a question mark appears. When it is plugged into a power source, the apple logo will appear, then a circle with an "X" through it appears. The screen then fluctuates between the two images, never booting properly. Any suggestions as to what is going on with my computer? My computer is 3 years old. This issue started happening after I installed El Capitan. Should I maybe try reinstalling my OS? I have a back up of my computer.