It's great that you were able to determine what was causing the problem and fix it. No need to eat crow, either. No one can find everything, even when they feel they should have. With all of the things that can go wrong with a system, remembering to check everything, and I mean everything, is practically impossible. Sometimes they can even be things you'd never imagine would affect the system. I'm just glad you figured it out and have your internet working again, and when you DO fix it yourself, like you did, the repair always feels that much more satisfying.
Besides safety issues one potential problem area for customers doing a self-repair is using the proper materials.
Coax needs to be solid copper center conductor, not copper plated. Connecters need to have dialectic grease applied and everything needs to be rated to 3 Ghz.