Default Boot script to turn on wifi tethering? flashable odin?

Hey guys i have kind of odd question.

but here's my problem. i have a Galaxy s4 SGH-M919 with 4.4.2 Google play edition rom and it thinks it is the galaxy s4 i9505 because it is the exact same as one, specs and software. i would like a boot script that turns on wifi tethering upon startup. the screen is absolutely destroyed because of a failed glass removal and i am unable to see the screen and use touch screen. i do have access to other Galaxy s4 SGH-M919 at my house because their my parrents, but i would like to use this phone's LTE as a hotspot while at school and other places. the home botton still works and so does volume up and down. i am testing ADB right now trying adb but i think it is blocked because i half to ok my computer.

Update: i have adb shell access through recovery and i can read/write system, data, sd card, ect. in android os i have adb access but not su, i think super su is blocking it... anyone how how to fix this? because if i can get su then i can make an app that simulates touches on the screen to open tethering
Thanks for any help