08-25-2021, 08:08 AM
The short answer is I don't think you can do that without significantly reworking the power subsystems. The modem (and the wifi IIRC) use a direct connection to the battery to more efficiently provide the high peak currents they can draw during transmission. There's quite a bit of discussion about the details of the power subsystems in the thread about pogo pin power. I think it included what could be done using USB power only.
https://forum.pine64.org/showthread.php?...+pin+power
https://forum.pine64.org/showthread.php?...+pin+power