These small, lightweight machines make great travel laptops. They get fantastic battery life and are very portable. Their one big flaw is the lack of proper Linux tools and a full Desktop Environment with the default ChromeOS installed, which is easily fixed with GalliumOS!
Read more about the project here: https://galliumos.org/
What you will need:
Flat head screwdriver
2 USB sticks
The very first step is to backup your data! Go and grab a copy of anything you wish to keep right now. We are going to be wiping all the data off this machine shortly.
Backup secured, the next job is to create a bootable USB image of GalliumOS. The Dell 3120 Candy contains a Celeron N2840 dual-core processor from the Bay Trail family so you need to grab the latest stable "Bay Trail" release from here: https://galliumos.org/download and burn it to one of your USB sticks using your favourite USB creator. I suggest Etcher, as it is cross-platform, but you can use anything you prefer.
Now we have our image we can start removing the 7 screws on the underside of the machine with the Phillips screw driver. Then pop a single layer of tape over the end of your flat head driver. This is to protect the finish of your laptop case, so don't skip this bit.
Next with your taped flat head screwdriver gently pry up the rear cover. Once you get it started it will come up really easily.
We are in here to remove the write-protect screw located left of the "WP" marked on the board here.
Now you have removed this screw you can reassemble the laptop and we can get to the fun stuff.
Laptop reassembled we are going to power it back up. When you are up and running again we need to enable developer mode and turn off OS verification.
To enable developer mode you need to hold Escape and Reload buttons down then press the power button once.
To turn off verification hold down Control and press D. Then hit Return to confirm your choice. The laptop will now reboot a few times and beep at you. Just leave it alone until you are back up and running in Dev mode.
When your machine has finished rebooting connect to your WiFi again and hit Ctrl+Alt+T or Ctrl+Alt+F2 and login as user: chronos
Using the https://mrchromebox.tech/#fwscript site as reference, we are going to download the custom Coreboot firmware script.
When you are in the terminal you can now enter:
cd; curl -LO https://mrchromebox.tech/firmware-util.sh && sudo bash firmware-util.sh
Choose option 3 "Install/Update Full ROM Firmware"
When prompted to backup your original firmware insert your spare blank USB and choose accept.
Once the backup is finished keep it somewhere safe and copy it to your existing backup solution as well (you do have a backup solution right?!) for safe keeping.
Having completed the custom Coreboot install you can now insert the GalliumOS USB installer we made earlier and reboot. You will get a live environment, just click the installer shortcut and follow the prompts.
From here on it's just a normal Linux install process and you are done!