Our Fantastic Fan 6600 with remote will not turn on with or without remote. I have changed the batteries on the remote and checked the fuse. Unable to re-pair remote with fan. If I understand correctly the fan should come on when I raise the vent cover manually but it doesn't. Looking for help on how to trouble shoot the problem. Thanks in advance.
Make sure you have 12 volts to the fan itself If you wired it off the original fan wiring there will be a circuit breaker or fuse.
Looks like the 6600R has both temperature and rain sensor.
Is the rain sensor fouled or damaged? That would cause the cover not to lift automatically (and thus the fan not to turn on).
There is a receiver circuit board in the fan itself. It might have gotten damaged or disconnected.
ETA here's how to retrain the remote if you haven't tried it https://www.etrailer.com/question-558732.html
There is a "Plunge Switch" that turns the fan on when the lid is opened. Very common for it to get dirty and not work. Open the lid & get on the roof and wiggle and twist the plunger around a little to get it to make contact. No need to replace the switch.
Plunge Switch (https://pantherrvproducts.com/dometic-fantastic-k1122-05-oem-roof-vent-plunger-switch/)