I thought I would make a recovery USB drive for my Samsung Chromebook II. First I tried at work, using the student wireless network. That was a flop, I tried three items to download the recovery image but it failed. The sanctioned instructions are here, https://support.google.com/chromebook/answer/1080595. I tried again at home and had the image in 10 minutes, installed to the USB drive shortly thereafter. It could also have been a microsd card, its just that I had a spare USB drive.
I have to tell you though I tried to follow the instructions and use another computer and it did not work. Seemed that I could not get the correct install image just from the model number. So the recovery plan became that I install the recovery tool and make the drive there. So I did, it chose the correct image to put on the drive at the time of making and made the recovery drive.
After that I thought well, now you made it but does it work! So, I looked up the key sequence for my Chromebook. That would be, from a not on state, hold the escape and the reload key while pressing the power key. I plugged it in and off it went. It began booting from the drive and begin a verification of the image. Now, you would think there would be a pause to let you choose to recover or stop. No, it went straight to recover and once started you may not stop!
Twenty minutes later I was rebooting the Chromebooks and signing in to my account again. A little code from the Google authentication app on my iPhone and enter your sync password and all your settings are restored. You may have an update happen right away if the image is not the current patch, as mine was not. but then your are just a reboot from getting back to work or, in my case writing a post.