Go to chrome://version on your School Chromebook to find your board. Look at the ending of the "Platform" section right after stable-channel. The word(s) after that is the platform you will be looking for in Step 2.

Step 3:

Download this on your Personal Chromebook. After downloading click the extension. Click the Settings button.

Step 5:

Go into RECOVERY MODE on you School Chromebook. While your Chromebook is doing it's thing and turns to the setup screen, connect to the WiFi, as soon as you do you want to make sure you keep pressing “CTRL + ALT + E” to make sure it doesn’t automatically update and proceed to sign in like normal.

You’ll know you have it if on the enterprise enrollment screen it looks like a blue bar with a briefcase.

Go to chrome100.dev on your Personal Computer and CTRL F search the word(s) AFTER "stable channel" and then press see more. Then download the version of chrome you want on your school computer. (I recommend version 81.)

Step 4:

Get a USB plug and connect it so that your Personal Computer is CHARGING the School Chromebook. Then in the Settings of the Recovery Extension, we just downloaded, press USE LOCAL IMAGE after you, School Computer is in RECOVERY MODE.