If you still want ChromeOS, try https://chromeos.google/intl/en_au/products/chromeos-flex/

If you want to boot a Linux distribution, try https://docs.mrchromebox.tech/

Along with farfatched's suggestions, you could look into Postmarket OS (based on Alpine Linux).

The devices page on their wiki shows compatibility with specific devices - https://wiki.postmarketos.org/wiki/Devices

> managed by a school […] and they failed to release the device.

This means you cannot install the alternate OS setups mentioned in sibling comments.

Throw it away.

ETA: info correct as of a long time ago. I have done no new research.

My son wants to throw it away, I want to at least try and reuse it.