As mentioned in https://linux-sunxi.org/PinePhone#FEL_mode the easiest way to enter FEL is probably via sdcard image. Otherwise you can enter FEL if you don't have a valid boot signature on the eMMC and no sdcard inserted. There is a testpad for the FEL pin (that you could pull low with some soldering and flying wirres) but I haven't checked where it is located on the PCB... for what purpose do you need to go into FEL mode?
If you just want to expose the emmc via the USB port, using the jumpdrive image is a lot easier: https://wiki.pine64.org/index.php/PinePh..._JumpDrive
If you just want to expose the emmc via the USB port, using the jumpdrive image is a lot easier: https://wiki.pine64.org/index.php/PinePh..._JumpDrive
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