Hi. Ive been using the Yale Conexis L1 lock for several years now and ive been fairly happy with it.
Recently because of an issue with the lousy app i needed to make factory reset of it and thats when problems started. After disassembly, the lock for factory reset and reassembling it, it was no longer closing/opening door - instead it was making that grinding noise (which it also does when the handle has not been fully moved up).
I have disassembled it again to centre the cogwheels and still the same. I have tried opening it, aligning the cogwheels and assembling many times, but every time i only had that grinding noise. At the end the cable snapped because of the opening and closing of the lock.
Then I have purchased a new Conexis L1, completely replaced all the mechanisms with the new ones as in the manual and… still the same problem with the grinding noise.
Has anyone had the same problem and managed to resolve it?
Yes, I had this, and still have to some extent. If everything is aligned as per the instructions - and mine was - then my conclusion was that the door itself was twisting/warping when the hooks were engaged (this can be proved/disproved by locking the door while it is open). If you think about it, the motor is only turning the small lever inside the door. Loosening that lever module a little using the screw in the door frame might bring some relief. In my particular case (because I have already had the company who fitted the door to adjust it several times) we’ve just resorted to putting a little pressure on the door in exactly the right place while the motor is turning, and this sorts it 
I have managed to resolve it but im not sure how, after dozens of attempts to assembly everything it just started to work.
But ive got a feeling this might not even be a hardware problem, but a software/firmware problem