I don’t have the circuit diagram for a D310, and there may be someone else on here who does, but most boat systems are the same.
1. Bit obvious, but nearly all windlass only work when the engine is running as they heavy battery/current draw. So if you have an engine problem and not running the engine, it probably wont work
2. I just looked on the circuit diagram for my D365 and there is a 5A fuse for the windlass remote control, so check that’s not blown
3. Bit drastic, but you can use car jump leads for a very short period of time to bypass the windlass solenoid just to check that if you get the power to the windlass it rotates. If it does rotate using this method you know its not the windlass (expensive) and something else in the control line (cheaper)
4. I actually had a windlass solenoid slowly go inoperative over a short period of time. I just noticed it was feed out much faster than it was hauling in even with the chain off the gypsy. The contacts inside the solenoid were slowly burning out. New one was about £70 from Force 4 and 15 mins to change it
If your engine is running OK, and its still not working check the fuse first and then hand controller relay, then solenoid and if all that is Ok with caution use jump lead to bypass solenoid
It’s always worth popping the breaker and remaking it or if you have a DVM (digital voltmeter) check its functional
Hope this helps, post how you get on