Q: Won't start. Good battery and alternator

About a month ago I was driving and the battery meter said it was on a high voltage. I pulled over turned the car off then back on and the light would go away.

Last week I noticed whenever I would go faster then 10mph the light would come on and it would go away if I came to a stop. Now, the car won't start. If I turn the key to on the lights come on and the windows work. If I try and turn the car on it does a click sound and I lose all power. If I try and do it again the lights won't come on. got it to start with a jump but I have to keep it gassed or it will stall. I took the battery to Autozone and tested good. Changed the alternator and still had issues.

I'm out of ideas. Good battery(fully charged) so the car should turn on regardless of a bad alternator. Bad started, maybe bad spark plugs?

Idk if this is relevant but I swapped my battery out for a friends and it started. Drove it around then the battery died and is no longer holding charge. Mine is still good though.

My car has 200000 miles.
My car has an automatic transmission.