Apple Watch S6 ECG problem

I have an Apple Watch Series 6 44mm Cellular model. My problem is that I can't make a proper ECG measurement. When I try it, the first 10-15 seconds starts the baseline moving without moving my fingers and my arms. Sometimes the measurement can up to 2-3 minutes and after 8 to 10 measurements says it has poor quality. I don't have any medical problem, because I'm an final year medical student. After 2 software update the problem is still there, I have written to Support, but I didn't get a proper answer. I came from Hungary, so I called the Irish Support of Apple and they can forward my problem to the US Support. It was about a month ago, and still no answer. I sent them diagnostics about my Watch, 5 ECG reports, the invoice if it is needed to repair or replace the watch. Can somebody tell me when I get the answer? Or is there any chance to replace it?