You might want to enter developer mode if you’re following the instructions in the Chromium OS Developer Guide, or if you just want to get access to a shell on your device to poke around. To get your device into Developer Mode, you’ll need to flip the developer switch to the “Developer Mode” position.

The first time a Chrome Notebook boots in Developer Mode after leaving Normal Mode it will:

• Show a scary warning that its software cannot be trusted, since verified boot is disabled (press Ctrl-D or wait 30 seconds to dismiss).
• Erase all personal data on the “stateful partition” (i.e., user accounts and settings – no worries, though, since all data is in the cloud!).
• Make you wait between 5 and 10 minutes to while it erases the data.
• Boot from any self-signed image on its SSD, negating the security of verified boot.

The erase and wait steps only happen when you first switch to Developer Mode, to help prevent someone from quickly reimaging your device while you’re away from the keyboard. Successive boots in Developer Mode will only:

• Show a scary warning that its software cannot be trusted, since verified boot is disabled (press Ctrl-D or wait 30 seconds to dismiss).
• Boot from any self-signed image on its SSD, negating the security of verified boot.

Entering Developer mode is easy:

1. Remove the battery.
2. Peel off the sticker that hides the developer switch (see image 1).
3. Flip the developer switch towards the battery connector (see image 2).
4. Put the battery back in.
5. Turn the device back on.
6. Press Ctrl-D at the scary warning screen.
7. Wait 5-10 minutes and any saved information on your device will be erased.

Congratulations, enjoy hacking in





[h=Sources]2[/h]

Chrome OS Site - How To Enter Developer Mode On CR-48
Google - Cr-48 Chrome Notebook Developer Information