Automated power on with charging cable plugged

For Non-Samsung phones

Turn Your Old Android Phone/Tablet into the Ultimate Car GPS (for poweron with charger plugged in, see 12:36)

Because Samsung can't do Fastboot the above method won't work for charger, but it comes down to going to fastboot mode and typing

  adb reboot bootloader
  fastboot oem off-mode-charge 0

Set your Android Phone to Automatically Power on when USB Charger is plugged in

Because Samsung can't do Fastboot the above method won't work, but it comes down to going to fastboot mode and typing

  adb reboot bootloader
  fastboot oem off-mode-charge 0

For Samsung phones

Auto-starting Samsung Android phone when charger is plugged in.

Ensure busybox is installed first Busybox by stericson Note also that if you install to /sbin you will lose it all after reboot, so install to /system/xsbin

  adb shell
  mount -o rw,remount /system

Note: start in recovery mode (twrp) and mount the system partition here. If the phone is started then you can't perform the /system remount.

  cd /system/bin

https://forum.xda-developers.com/galaxy-s7/help/samsung-galaxy-s7-boot-charge-t3680083

https://android.stackexchange.com/questions/195146/lpm-reboot-samsung-galaxy-s7/206872#206872

Note the above guy uses 'echo lpm.sh > lpm' commands, which won't work - you have to cat them over!

You can't just copy stuff over /system/bin/lpm presumably due to inode problems. If you do, when you plug in the charger you will only see and empty battery picture. So you need to create the script, and then cat the script over the lpm file

  cat lpm > lpm.orig
  vi lpm.sh

#!/system/bin/sh
/system/bin/lpm.orig &
while [ true ]; do
 
 bat_proc=`cat /sys/class/power_supply/battery/capacity`
 
 if [ $bat_proc -gt 10 ]; then
 sleep 3 && echo b > /proc/sysrq-trigger
 fi
 
 sleep 5
done

  cat lpm.sh > lpm

  chmod 0755 /system/bin/lpm.orig
  chown root.shell /system/bin/lpm.orig

exit adb

  adb reboot

power off