i just went through that. my 2020 gmc sierra elevation.
did exactly what u mention above and completly died. I locked my truck went inside and came back out now it Wouldn't unlock my door.
Then I used my key from fob to open it ... jump started the truck and it took 5 min to start. finally it started ....now i have engine check light on...also just got an email i bought it 30 min later that my truck has antilock breaking system issue. but i dont think that should kill the truck completely.
no way it could be the battery....monday will be taking it to the dealership.