Did you make sure the flat on the rod engaged in the new angle sensor before tightening up? If so I’m afraid that trial and error or take it to the dealer are your options now. Does it change up and down with the emergency lever? They are always stiff as the lever has to turn a reduction gearbox and the motor as well, but a reluctance to change manually indicates a common mechanical fault in the selector mechanism. The pawl that moves the starwheel can crack, and springs out of the way when you try to change gear. Honda changed the design, so know about the fault but the later type still breaks, a female splined lever moves this pawl and I have known that to crack as well. They are in the clutch housing, but oil pipes are in the way and I rather think I had to remove the clutches to get at the pawl. The star wheel can also come loose so check that the setscrew, in the centre of it, is tight. I always Loctite the screw in if I have removed it.
If it changes OK manually, the earlier fault code indicating the up down buttons could be correct, or it could be a faulty shift motor, an earlier post on the forum explains how to strip it, or the wiring could be at fault. Finally the ECU could be failing, particularly if the voltage regulator is putting out over 15.5 volts.

 

Thanks for the replies, think I am headed to the dealer

 

Pull the shift motor out atv with the harness still connected an ground it to the frame or engine ground then shift an see if shift motor shifts.If does then take the gears out of shift engine mount housing sometimes the moly lube honda uses is to stiff or get containated clean out all old grease an put new moly lube back in BUT before you put moly back in mix it with an lil bit of gear oil.{ NOT TOO MUCH}.this seem to help me with moly not being too sticky works fine in all of the ones I have done..Good Luck