Chromebook Recovery

Chromebook would not turn on

I was recently telephoned by somebody whose ASUS Chromebook (model C523N) was no longer turning on properly, so agreed to visit to investigate the problem on my usual ‘no fix, no fee’ basis. When I arrived at the customer’s house to pick up the Chromebook, he demonstrated the problem and it was clearly not fixable instantly, so I took it away.

First the Chromebook logo, then nothing

When turning on the Chromebook, a ‘Chromebook’ logo appeared, but then the screen went blank after a few seconds. Close observation revealed that the screen was not totally blank, but cycling constantly between dark grey and black. This effect was hardly noticeable, and was probably caused by the display’s backlight being turned on and off.

Occasional flashes of a login screen

Sometimes, when repeating the attempt to start the system, a login screen would eventually appear for just a fraction of a second, then instantly disappear again without there being a reasonable chance to read anything in detail. The only way to see what was happening would have been to video the screen then review the video frame by frame.

Hard reset procedure did not work

The next step was to try the ‘hard reset’ procedure, which simply consisted of holding down the ‘refresh’ button while pressing the ‘power on’ button, but unfortunately this made little difference except that once I saw three on-screen buttons appear at the bottom-left, though they disappeared before they could be read, just like the login screen.

Recovery image was very large

It is possible to download a recovery image of the ‘chromeOS’ operating system onto a USB flash drive or SD memory card with a capacity of at least 8 GB, then use that to reinstall the whole system. However, my Internet connection was not stable enough to download such a large image in one go without any interruption, so that was a last resort.

Could the Chromebook run Linux?

Even so, I needed to know whether reinstalling the entire system was feasible, so I held down the ‘esc’ and ‘refresh’ keys while pressing the ‘power on’ button to see if the system would go into ‘recovery mode’, which it did. While in recovery mode, I tried to run Linux from a USB flash drive, but the system complained that it was not ‘chromeOS’.

Trying to drain the battery

It occurred to me that the Chromebook had never been physically exhausted of power, since even when it was ‘off’ the battery was still supplying current to the main circuit board. Draining the battery completely might solve the problem by losing all the contents of volatile memory. However, the Chromebook kept switching itself off after a short time.

Battery would not empty overnight

Putting the Chromebook into ‘recovery mode’ overnight left the screen on, displaying a message asking for a USB flash drive or SD memory card containing a system recovery image to be inserted. I hoped this would exhaust the battery, but when the charge reached a low level, even the ‘recovery mode’ that had been on all night turned off to save power.

Chromebooks try hard not to empty their batteries

At that point, trying to start up the system normally, or in ‘hard reset’ mode, just caused a ‘low battery’ icon to appear, after which the system shut itself off. The Chromebook seemed reluctant to do anything that might drain the battery completely, so the only way to deprive the system of all power was to take it apart and disconnect the battery.

Going into Developer Mode cleared all local data

Before taking the system apart, I researched what could be done in ‘Developer Mode’. Going into the ‘recovery mode’ then typing ‘Ctrl + D’ would put the system into ‘Developer Mode’ so I tried that. The system warned that ‘Developer Mode’ was not secure, then when I asked to proceed, the system cleared all of its ‘local data’, which is what I wanted.

After returning to Verified Mode, everything worked

After that I asked to go back into ‘Verified Mode’, and the system then rebooted itself. Once the system was back in its normal mode, it booted properly as if it had been factory reset. No user data had been lost, as there was nothing stored locally (it was all in ‘the cloud’) so the customer could re-connect the system to his Google account and carry on.