After a powerwash, run through the prompts that are presented in regular usage, set up wifi, and allow the machine to contact google. If the device has been legitimately sold off, the enrollment should drop, and regular login and guest mode should show up in the bottom left corner. If this works, you can then set it to developer mode. If not, you can wait, try again in a few months, but it is likely that the machine was marked stolen at some point.

After a powerwash, run through the prompts that are presented in regular usage, set up wifi, and allow the machine connect to wifi and contact google. If the device has been legitimately sold off, the enrollment should drop, and regular login and guest mode should show up in the bottom left corner. If this works, you can then set it to developer mode. If not, you can wait, try again in a few months, but it is likely that the machine was marked stolen at some point.