I have a Dell Latitude 7480 that has been having power issues. In early august, I noticed that when the unplugged laptop dropped below 80% battery, it ran slower. Videos and audios lagged, and it struggled unless it was plugged in. But it also overheated when plugged in. The scariest part was that sometimes the laptop just shut off abruptly. I would have to take the battery out and put it back in to bring it back to life. It was also insanely slow to charge.

I bought a new battery, and I also noticed that I was having some strangeness with the charge port so I replaced that and the AC adapter as well. It no longer overheats when charging. I can use it below an 80% battery. However it still sometimes becomes impossibly slow to charge and shuts off randomly. Sometimes my laptop behaves normally, like new, for exactly 24 hours before remembering whatever issue it's having and acts up like this.

My last attempt to fix it was today, September 1st. It shut off at 78% so I took the battery out, held the power button for 10 seconds, left the battery out for 5 minutes, and then restarted the laptop. It's currently charging as normal. What can I do to fix this problem?