Sennheiser Momentum True 4 Headphones Stopped Working After Warranty

When I tried to use my Sennheiser Momentum True 4 headphones on September 23, 2025, I noticed that the device wouldn't connect at all and there was no sound. Since the problem began, the headphones have been completely inoperable. I tried resetting the headphones and charging them for a long time to resolve the issue, but I haven't received any results. The product's warranty has expired, and I don't have any receipts or proof of purchase. I don't expect a solution from you, but every Momentum True series product to date has had issues. I've used models 2 and 3, and they all malfunctioned. Since my warranty has expired, there's nothing I can do. Of course, I don't have any documentation, but the sound quality may be the best, but this many errors and malfunctions are not normal. As a company, you can see this if you do your own research. I want to share my dissatisfaction with the fact that this problem is constantly occurring and the headphones have become completely dysfunctional.