I replaced the screen with a known good one and it worked for 1 boot

I would check the Lid sensor at this point. The Hall sensor is located on the logic board just above the USB-C sockets in the outside corner. It’s on the backside so you can’t see it without taking the logic board out

To test things you can use a rare earth magnet sliding it across the top surface of the uppercase. To help locate the area take a steel paperclip carefully sliding it across the face of the display, you should note the magnet grabbing the paperclip. Now take note of the location using a piece of tape, then fold the display lid down to find the location on the uppercase so you can slide the magnet across.

If you have a second system give it a try there first so you get the idea.

Sadly, it only reacts when you bring the magnet to the sensor to turn the display off (Clam Shell Mode) in this case that won’t help you as the sensor is stuck in closed mode.

You could see if the sensor has a cold solder joint, otherwise this is a logic board replacement, and the display was likely OK.