@Macattack 

You need at least 1 EAP225-outdoor connected to ethernet if you want to adopt another one remotely via Mesh.  You can also adopt an EAP225 while ethernet connected and then deploy it to the field wirelessly.

Regarding the 'reset'....there's reboot and factory default.  To make sure you're going all the way back to factory, you need to depress and hold the tiny button beside the EAP225-outdoor's ethernet jack for ~10s.  After this, you should be able to easily adopt it via your controller.