The button on the back of your Grobo has many functions.
Unlocks Your Grobo: Hold the button on the back of your unit for 3 seconds. After this your LED light should turn blue then your door will unlock. Learn more about unlocking Grobo.
Reset WiFi: Holding the button for 8 seconds will disconnect your Grobo from the Wifi. This is used when you’re moving your Grobo to another network. If you do accidentally hold this for too long and disconnect your Grobo, you will have to reconnect your Grobo through the Settings page on your app.