A short while ago, we bought each of our daughters an Acer Chromebook C514 so that they could do their schoolwork remotely during the lockdown. These were reasonably priced and had good reviews from what I could see. They’ve been working fine for the last month or two since we received them.

This morning one powered hers up only to be greeted by an alarming screen stating “Chrome OS is missing or damaged”. The documentation suggests that in this case, you’ll need to reinstall the OS.

Hitting TAB at this point will display errors. In this case I could see the following amongst other things:

...
recovery_reason: 0x2b / 0x2b Secure NVRAM (TPM) initialization error
...
TPM state: communications error

First off, I tried following the instructions by downloading an appropriate recovery image onto a spare micro SD card (might be worth keeping one around, >= 8GB in size, in case you need to do this).

Booting to the recovery console (by pressing ESC + Refresh + Power) and inserting the card started the recovery process, but this failed with another error: “The security module on this device is not working”. The Google documentation then ceases to be useful, suggesting possibly contacting the manufacturer or asking on the forums.

There are various threads on the forums and across the internet covering possible solutions - including turning it off and on, not just once but 20 - 30 times, which just seems ridiculous.

In the end for us following the battery disconnect actions as follows successfully reset the TPM module:

  • Power down the laptop;
  • Ensure the laptop is connected to mains power;
  • Boot to recovery by pressing and holding ESC + Refresh, pressing and releasing the power button but continuing to hold the other keys;
  • When the laptop shows the screen asking you to insert the SD card or USB stick press and hold Refresh + Power, remove the mains power, then release the keys. The laptop will be shut down in battery disconnect mode.
  • Plug the laptop back into mains power and start it up. With luck, the TPM module will be reset and it will boot normally - no need for a re-install.

I have a horrible suspicion though that I’ve not seen the end of this, I can’t quite believe it is really as simple as that.