IIUR, you have installed arch to emmc?
If this is so, disable emmc, insert debian SD, press and hold pwr (20+ sec), try to start (1 sec press)
If this works, change arch pinebookpro dtb for manjaro dtb (on emmc of course)
BTW, for a hard power off, it is a 7-8 sec press of pwr, for reset it supposed to be 15 sec, this is not long enough
I think, because there is a battery, it remembers something that is wrong
If this is so, disable emmc, insert debian SD, press and hold pwr (20+ sec), try to start (1 sec press)
If this works, change arch pinebookpro dtb for manjaro dtb (on emmc of course)
BTW, for a hard power off, it is a 7-8 sec press of pwr, for reset it supposed to be 15 sec, this is not long enough
I think, because there is a battery, it remembers something that is wrong