Don’t be discouraged, thousands of us use these machines every day with no problem. Both machines I have used over 9 months calibrate in about 2 minutes. Every time.
Regarding the teal button, see if This video helps.
More often than not, failure to calibrate reflects spotty WiFi. When you turn it on the machine images the bed and sends that to the Cloud Server. The server responds with instructions to move the head under the camera. The machine moves the head and the camera images the bed again and sends that back to the server. When the server sees the GF logo on the head is directly under the camera, then the server is satisfied it knows the exact position of the head and the Machine is calibrated.
There is a lot of communication back and fourth between the machine and the server, so a good wifi connection is required. When there is a problem calibrating, it is natural to assume there is a problem with the machine, but most often that isn’t the case.