My Chamberlin garage door opener MyQ has:
Item # 737047
Model # C410

The protocol

1.	Try to loosen the chain and 
2.	Disconnect the wall control
3.	Test which two wires (red and white) are for the wall control
4.	Test the learning – make sure it works
5.	Possibly check/adjust the chain tension
6.	Connect the wall control – make sure it works
7.	Figure out the safety sensor, how to wire, etc. 

Here are a few helpful tutorial links:

https://www.handymanhowto.com/chamberlain-belt-drive-garage-door-opener-review-part-3/


https://www.youtube.com/watch?v=6Nd9DtDdb_M