Booting mobian and postmarketOS on pinephone

I have used postmarketOS on pinephone (2gb) by installing to SD card. Recently, I install Tow-Boot and mobian in the internal eMMC as the original Linux OS becomes unuseable after a software update. By default, the pinephone always boot up the Linux OS on the SD card. We need to remove the uboot software at the front of SD card first before Tow-Boot can boot up mobian by default, and boot up…