Xiaomi Mijia Window Cleaning Robot Malfunction

I purchased a Xiaomi Mijia huttdc55 window cleaning robot from Teknosa. It worked the first time I used it, but a week later, it stopped working, showing a red light. I contacted Teknosa, and they redirected me for a return. After sending it back, I was told that water had seeped inside, causing oxidation, and that it was a user error.

When cleaning windows, you spray glass cleaner on the window and wash the mop cloths before attaching them. How can they make a product that lets water seep in? Moreover, how does oxidation occur in just one week in the heat of July? The repair cost requested is ₺7500 + VAT, while the product itself costs ₺7900. Essentially, ₺7900 went to waste. How can I find a solution?