The only time I've bricked a Pi ever was when I shorted 5V and 3.3V rails in a 3B+. A friend always talks about one bricked with an apt upgrade by a broken firmware or something, never seen anything like that. Saw plenty of dead or corrupted sdcards but that can be fixed with a new one, which doesn't seem to be your case. Maybe a bad power supply? Pi is a bit picky, you need one with 5.1V to prevent low voltage warnings.