Since you don't have your original remote, are you able to confirm what radio receiver you have installed. Please call our office if you need further help @ 800-676-4909.

Here is the manual for that: https://cdn.shopify.com/s/files/1/1666/9427/files/Liftmaster_371LM_user_manual.pdf?v=1631634539%20

No, it would be the 971LM. https://pssstore.net/products/liftmaster-971lm-1-button-remote-control-390mhz?_pos=2&_sid=ece405db0&_ss=r

There can be a number of reasons they are not working. It could also possibly be your radio receiver that is having the issue.