That's a defect, and the seller is just trying to dodge their obligations. They don't need a video from you, because a coffee maker is supposed to work in the first place, not work well if you use it properly. Those are two different things. The law protects the buyer in these situations, and Yandex Market knows it.
Write a complaint to the seller in writing - better through the chat in the app so everything is documented. Tell them the product has an obvious manufacturing defect, won't turn on (or isn't working, depending on the issue), and you're demanding a refund or replacement. No extra explanations and no video. If they keep insisting, go straight to filing a complaint with the platform itself.
Yandex Market has built-in buyer protection. Go to "My Purchases," find the coffee maker, click on the issue, and file a complaint right through the app. Specify that the product hasn't worked since you received it. Market will look into it and force the seller to accept the return - the platform doesn't care at all if the seller refuses, because they're liable to you. In my experience, these issues get resolved in a couple of days in the buyer's favor if it's clear-cut.