This tutorial is for reference only, forwarded to indicate the source
I used here is Dell this 11 3120
1. The teardown
Unscrew bottom a few screws, card slowly pry the edge of the floor, find a written WP screw, this is to protect written screw, put it off to
2. The developer mode
At the same time holding down the esc + refresh button + power button into developer mode
A line of words appears call you insert usb device, direct and press Ctrl + d
Then press space to restart, can be directly and press Ctrl + d
Then call you press enter to enter, will wait for a few minutes
Then we will enter the login screen, we can enter the visitor pattern
After entering the Ctrl + Alt + T at the same time open a terminal
The input code sequence is as follows, please notice here with are in English symbol
1. The shell
2. CD ~/Downloads/
In the Downloads folder, it put inside the corresponding BIOS file
3. The sudo dmidecode - s system - the product - the name
The third step will display your model code, we write it down
We need to download a BIOS file, the link I will put in at the bottom of the article, there is a text will be a corresponding model code download links, oneself have to do is find after download, the default in Downloads, I also recommend here
4. Sudo flashrom - r BIOS. ROM
Backup the original BIOS file, afraid of brick can brush back
5. Sudo flashrom - w filename. ROM
After I send the link to download a. ROM file, because the name is longer, we can change to shorter convenient operation
6. Shutdown restart
Then we will see the entry is not Chrome OS, but it is a white mixed with some black icon, here we even brush third-party BIOS success
7. Production startup disk, I recommend using Rufus, tutorial baidu to check
8. We insert making good startup disk, boot icon below a line of words appears, we point the esc, and then point number down on a second, find your U disk, point the enter can begin to install ubuntu

The BIOS file download link: https://www.lanzous.com/i9pmoxi

Tutorial is after a brush to write, and have a look not to know in the comments below message