I can’t get my MacBook Pro to charge

Yesterday while working like normal, my computer suddenly shut itself off. It was around 70% battery and plugged in/charging.

When I turned it back on, the fans were blowing at 100%, and it was only on for a few minutes, before it shut itself off again. I tried turning it on one more time to see if I could figure out the problem. I was only able to check the battery condition before it shut itself off again. Oddly, it said 0% power.

The computer shut off again, I unplugged it and decided to give it a little break. Some research said it might do this when it overheats. Some other people said it might do this if the charger goes bad and is delivering inconsistent voltage.

It wasn’t particularly hot, but I let it cool down and unplugged the charger. After letting it sit like that a while, I booted into safe mode. It worked just fine, so I rebooted like normal. Everything worked fine! I was back at close to 70% battery, and the fans weren’t working overtime. I tried plugging it in, and…nothing. The charger didn’t work at all.

Based on what I read, I just assumed it was a bad charger, so I ordered a new one. It arrived about an hour ago, and it surprisingly also does not work.

If I plug in the old charger, I get a very quiet high pitched noise about once per second. You can only hear it if you put your ear up to the computer, and it’s accompanied by a very quiet purr–like a fan noise (computer is off and dead now, btw). When the new charger is plugged in, you don’t get any noise at all.

As far as I know, I did not do anything to cause this. I wasn’t overdoing the computer when this happened. What are the first things I should look for in diagnosing this problem?