Without TWRP, adb devices shows no device connected. "fastboot devices" also produces nothing in Samsung Galaxy.
But in TWRP recovery, "adb devices" show "52034c5afabcc377 recovery".
adb shell ls at root shows directories. But adb shell cd /system and adb shell ls shows no files.
Question: why devices in recovery in TWRP fail to list files?
adb shell
only once