Yeah, I was thinking the same thing. I’m going to have them look at it when I go back to get the sound system tuned. I googled it and found a procedure for older accords, that involve cycling the car on and off and clicking the lock button. Just wondering if the 10th gen had something similar.When you say "keyless entry isn't working" do you mean when you push the lock/unlock button it's not responding? Does your car still start w/the remote transmitter in question? I would think if the car is starting then it's still programmed to your car.
Will your doors lock/unlock when you push the button on driver's door? Since this happened when the sound system was installed I'd lean more to something wasn't connected back during the installation, fuse blown, etc. Good luck on getting it figured out.