SM-T237P Samsung Galaxy Tab 4 Boot when plugged in

I have a SM-T237P Samsung Galaxy Tab 4 that I want to modify to Boot when plugged in / power is applied. I have the phone rooted but cannot find a way to access the file needed to modify. I want to mount and wire the tab 4 on a vehicle to use for navigation and want the device to start up every time the vehicle starts and sends power to the tablet.