Hello! This is my first post and I also don't know a ton about computers, so forgive me if this comes off sounding dumb. Just need guidance asap. Recently, my MacBook Pro 15" Retina (early 2013) (macOS High Sierra 10.13.3) has been having some issues. It all started about a month ago when I kept getting GPU kernel panics whenever I was doing something such as editing a picture/video clip, creating a PowerPoint, watching a video, etc. It kept happening over and over so I looked into it and read something about downloading "gfxCardStatus". Probably dumb but I was desperate as I'm a university student and need my laptop to work every day. This seemed to help for a few weeks and I didn't have any issues. Then about a week or so ago, my laptop would run fine and then start shutting off. I couldn't use it for more than 20 minutes before it would just shut down randomly. Then one-day last week, it shut down but wouldn't turn back on. I could hear the bootup chime (possibly incorrect terminology - but the screen was black, this was before the apple logo would turn on) clicking like it was trying to start up but it kept getting stuck. My laptop was like this for a few days as I couldn't turn it on. Nothing would work (tried holding down different keys - "D", "command + D", "command + option + p + r", "shift + control + option", etc. I tried it all). Finally, I saw a video online where a guy held down the power button for 10 seconds and then immediately plugged in the power while still having his finger on the power button for another 10 seconds. I tried this and it worked! However, the fan was running EXTREMELY fast/loud, and if the power source got unplugged my MacBook would shut off. There is NO Apple store near me. Closest one is about 2 hours away. However, there is an Experimac store. I took it there and they ran some tests. They said it was the battery. They put a new one in and all seemed to be working fine again....but then 3 days later it shut off and did the exact same thing. So, I took it back and they claimed it was a bad battery. They put a new one in, and it seemed to be working fine. Then, about 10 hours later, it did the exact same thing. So this is where I'm currently at. It won't let me run a diagnostic on it. Says that it can't. However, if I press "command + D" and run an Internet Recovery, I got this message: "Alert! Apple Hardware Test has detected an error. 4HDD/11/40000000" Please help! Need my laptop to work for school. This has already made my life super difficult.