Start with the hotel & work your way up. If it was my problem, which it isn't, I would commence research and go from there if I thought the time, effort & expense warranted it. Marriott, in extraordinary times or not, is simply a hotel supplier for their brands. Unlike a travel agency that collects money and pays the supplier, Marriott is a booking system that doesn't collect your money to pay their hotels or franchisees and it certainly doesn't have jurisdiction over foreign goverment. I doubt a CC chargeback, if within the dispute time frame, would be successful based on the same premise.

James