Dave,
Unfortunately a new boat is not like a new car, because "add ons" are usually covered by the original manufacturer. That said document everything (names dates times etc although I believe you are doing that) Check warranty info that came with the boat. I believe you'll find Humminbird is a separate company with separate warranty and bps may not be an approved repair center. Humminbird would be responsible for your electronics. (thats why BPS sells all sorts of electronics. If it was an installation problem, then BPS, or the factory I believe would be responsible, but I can tell you as a former sales guy for Humminbird, you need to put the ball in their court and have them tell you to contact BPS.(get names and dates you communicated) When talking with Huimminbird and they want to redirect you to BPS, ask if they have a contact at BPS you can deal with directly. As far as Nitro, I'll echo what others have already said,
Kent's the guy. He may even have you contact the humminbird rep. Although after watching your video I believe its in the wiring from the battery to the connection up front and on the dash. I know this sounds stupid, but check connections from the battery forward. Humminbirds are great units, but like all great things every once in awhile a dud comes out.
https://www.humminbird.com/
Your answers are probably there. Good Luck. I know its frustrating, but thats the world of fishing