nvidia shield portable prototype 2 with tegra x1

i have an nvidia shield portable 2 prototype it will turn on but after the nvidia logo shows up for bout 15-20 seconds it goes to a black screen and i can’t do anything. i have tried to boot in to the recovery mode and nothing happens. since it is different from the first nvidia shield portable the button layout is different in the middle. I don’t know if they change the way to boot into that mode or what. i have tried connecting it to my computer and the computer calls it APX. i don’t know to do can anyone please help?