Garage door opener replacement questions

I think some electronics in the motor have gone kaput. The wall mounted button works, but I have 2 remotes and neither works. (I did change the battery on one as well as try to re-pair it with the motor, to no avail.)

My options are to replace the circuit board ($125) or buy a new motor unit ($199). The original motor is a Liftmaster and the lift is a belt; it's probably about 20 years old. The cost of a new motor unit is not hugely more than the circuit board and I would get additional features like a battery backup.

If I go for a new unit will it work with the existing belt? I'm looking at a basic 1/2hp Chamberlain. Thanks!