Xiaomi Major Customer Service Problem for an Under Warranty Product!

I bought a Smart Band 8 in March 2024, and now the watch does not turn on. I purchased the product from mi.com, the official site. I have the invoice, but it does not include the serial number of the watch. Because the service personnel don't have access to the serial number, which is the fault of Mi for not including it on the invoice, I am unable to get service for my watch. I have called the customer service center and even traveled to the nearest service center to explain my situation, but I received the same result. I am left with a "smart band" that doesn't work, is still under warranty, but cannot be serviced due to their invoicing mistake.