Contact the manufacturer. Send them the video, tell them the dealer won't return your calls, and ask for a referral to another dealer.
I had a similar issue with a vacuum cleaner. I documented all my issues, the number of times I had been in to the dealer (14 times in 12 months), his responses, and the proof I gathered showing that he never touched the machine despite telling me he had fixed it - multiple times. They sent me a new machine and I believe the dealer lost his dealership. I don't know that your situation is as severe as mine, but the manufacturer might be interested in knowing about the lack of response from the dealer, and they may be able to troubleshoot the machine for you.