I’m sorry that you’ve run into trouble and your unit is showing a persistent cooling error message. To investigate this for you, I’d like to take a look at the inside of your unit as well as the connections to your print head.
First, there are two key connections I’d like you to check for me. Could you please do the following?
Turn off your Glowforge.
Holding only the finished black surfaces, grasp the printer head as shown. Pull gently up and back to disengage the magnets and remove the head.
There is a small tab in the center of the wire ribbon. Push down fully on the tab to release it, and gently pull the wire ribbon plug from the printer head.
Pick up the printer head and wire ribbon. Make sure the tab on the wire ribbon is facing up. Slide the ribbon back into the head until it clicks.
As shown, lower the printer head over the metal plate so that it rests next to the two round posts. Then push it gently away from you – you’ll feel a “click” as magnets pull the printer head until it sits snugly atop the metal plate.
Move your phone or camera inside the Glowforge on the left-hand side, past the metal rail, pointed away from you towards the exhaust hose, to capture a photo like the one below:
A photo of where your exhaust hose attaches to the Glowforge, where your exhaust hose exits the room, and the path your exhaust hose takes from your Glowforge to the exterior vent or Compact Filter