Hello man, I've got the same issue 3 days ago...
Check with your cellphone's camera if your remote is sending the command to your receiver. (Focus the front led of your remote with your cell, it can see the infra red light)
If not, (I'm pretty not,) you must open your remote and clean the circuit and silicone corresponding to not working buttons . Before close the remote check again with your cellphone's camera.
Tip: start opening the remote from the front, right beside the IR led.
Best regards,