So I took a logic board out of my partially working S6 Edge+ (has no serious issues) and put it in the phone giving me problems. It now does not freeze or reboot. That pretty much confirms it was the logic board that’s gone bad. The only thing that remains is the faded boot screen image. I read that’s something called “LCD/OLED burn in”. Not too bothered by it. It’s noticeable, but not enough to affect the usability.
So yeah, it was the board. Just thought I’d post an update.