Install gnome-firmware:
sudo pacman -S gnome-firmware
then run from terminal: sudo gnome-firmware
you get a gui where you can flash the modem... make sure you are connected to a charger
see here: https://wiki.pine64.org/wiki/PinePhone#Firmware_update
and here: https://forum.pine64.org/showthread.php?tid=16567
sudo pacman -S gnome-firmware
then run from terminal: sudo gnome-firmware
you get a gui where you can flash the modem... make sure you are connected to a charger
see here: https://wiki.pine64.org/wiki/PinePhone#Firmware_update
and here: https://forum.pine64.org/showthread.php?tid=16567