Refused repair - Xbox One S won't power up

Hi evergone

Just looking for some advice. I bought an Xbox One S 1tb back in January this year. My partner annoyingly gets rid of things as soon as set down, including the box where I had put the store receipt.

When it was about 2 days old, I had a problem where it wouldn't power up. It kept switching back off again, and I was getting ready to take it back when it started working and I couldn't recreate the problem so forgot about it.

I don't get time to use it that often, maybe 4 evenings a week, so it's barely used as we have another xbox connected to the main TV in our household. It's therefore always kept in a closed TV cabinet in my bedroom, away from things like dust and it's well
ventilated.

Anyway. Friend came round and wanted to play Gears. Brought my xbox and TV into front room and it won't switch on. It powers up for a second and then goes off. I followed all the advice online about resetting the power supply but if anything it made it come
on for a shorter time.

I looked online and it seemed like a common problem. Great I thought, it's under warranty for a known issue.

I sent it off to Germany for warranty repair, seeing as I had no store receipt. It came back today with a note saying they couldn't fix it as it was either tampered with or something else which would mean it can't be repaired. I called support and they couldn't
tell me anything except that it was something I had done, which I definitely haven't. I am the least technically minded person ever, so I would never tampef with it, and neither have I spilled anything on it or dropped it.

I feel as though I'm being called a liar and it's a real let down by a reputable company that I have spent a lot of money on (as a family we have 4 xbox ones with subscriptions), and I'm loathed to give another penny if I'm honest. I can't understand what
has happened to the console. Nothing happened to it since the night I used it and the next day when I moved it and it stopped working. The plug sockets where I moved it to are all fine and I use a surge protector anyway.

Is there any way that support can contact the servicing team to ask them exactly why it can't be fixed, so I can at least contest that. As the advisor told me they get no info and it's in the letter. The letter is a generic cover all thing that doesn't tell
me much except that it's excluded from service.

Also does anyone know what can be done with the console if I can't get this sorted, just sell it to be harvested for parts? Or could the power supply be fixed easily and cheaply by a third party? If I cab prove that it's a hardware fault with an independent
3rd party could I claim the costs back?

:)