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3- Custom BIOS

Image icon InsideAcerCB5-01.JPG183.15 KB
Image icon InsideAcerCB5-03.jpg76.64 KB

For those upset by the noisy sound and 30 seconds "scary white screen" of the developer mode, a little hack make you disable the sound and reduce the display time.

Be aware that you can brick the device if something is done wrong.

First you need to open up the device in order to get your hands inside so remove the 13 screws. Compare to other laptop, it s quite easy. Don't get angry, play with the shield case. Just go slowly, smoothly, like with a nice girl and if it doesn't work one way, try by the other side. At the end you ll make it you respect it. 

Here is a picture of the inside:

To make the BIOS writable you have to disable a hardware protection. It's a screw you have to remove and scratch the metallic round sticker under it until you see there is no full connectivity on the round solder. Do not put back the screw and remount the case of the CB5.

Switch on the chromebook and enter a terminal with "Ctrl + Alt + t"

In the terminal type the command:
cd ~/Downloads/

flash out the bios:
flashrom -r bios.bin

write the special flag to the BIOS:
gbb_utility --set --flags=0x01 bios.bin

flash in the new bios:
flashrom -w


Now if you reboot, the "developer mode" screen will only appear for 2 seconds.

More details can be found at