Diagnostics Freezes, battery is dead and shuts off on high loads.

Thank you so much for your response :) After looking around and reading your response, I agree with what you are saying. However there still is 1 issue, when I run diagnostics the laptop freezes(Maybe this is due to the battery too?), that is the reason the Apple Store said the logic board failed, but it sees reasonable to me to assume the low power or something like that is causing the issue as my Mac runs MacOS Catalina with no problems. My question now is should I just send in my Mac to the Apple store for a $199 battery replacement, or should I try it myself? I am 15 years old with no experience repairing devices, I do work with Arduinos however I don't know if that will help in repairing. Another thing that is bothering me is if the battery could just be unplugged as it was doing just fine days before it stopped working(before summer the health was over 70%), maybe I should just buy the tools(total under $50) and just check if it is unplugged as that part of the tutorial doesn't seem to hard. Thanks again for the help, I was actually thinking about saving $800 or more for the new ARM Macs and you may have just saved me $100s.

I have 2 15" 2015 models which I use in the field. These are still the best MacBook's Apple has produced! Hang onto it for now!

As far as the battery I would recommend you talk with your parents before attempting replacing it as it does involve using a solvent to soften the adhesive and you do need to use care taking the battery out that you don't damage it in the process. It's not overly hard it does take a bit of patience & strength. Here's a great vid of my friend Kay-Kay at iFixit fixing her own MacBook Pro Is Replacing the Battery in a MacBook Pro Retina Actually Difficult? She is a very slight person compared to me (6'6")

@danj After some thinking and talking with Apple support, I will probably just send it to them to be safe. There is still one thing I am concerned with and that is the diagnostics freezing, any idea on what that could be? - Thanks

@Salar Sheriff - If you handed me your system I would plug in a spare battery I have to see if the system was stable with it. Then if not I would dig into the logic board logic testing the different power rails.

But! In most cases issues like your's running heavy graphics or processing or even running diagnostics aim me to the battery issues. Rarely do I encounter power issues like yours that are deeper logic board problems.

When you go focus on the battery issues. Leave the diagnostics to them.

Thanks again Dan. I just got my MacBook back from repair and it is working very nicely. It was the battery after all. You saved me so much money and for that I am very grateful :) Without your knowledge and help I would have kept believing that the logic board was faulty and may have have spent $500 on it(or straight up buy a new computer). Your help was greatly appreciated :)