No keyboard or trackpad out of the blue

I'm troubleshooting an issue where neither the keyboard nor trackpad are working. Nothing has happened to the machine and it looks pristine inside. The user said she was using the machine and they just stopped working out of the blue. Can't do any resets because the keyboard doesn't work. Tried disconnecting the battery but that didn't help. Any ideas? I'm thinking it might need a new top case, but that's a $100 gamble. My other thought was replacing the cables to the trackpad and keyboard (Where is that keyboard cable? Didn't see it mentioned in any of the guides).

Thanks for any input, cheers.