Xiaomi Mi Router 3g (mir3g) - dead - no power

Hi guys!

Today my mir3g just would not turn on any more. The night before it worked normally.
I did not change anything.

Now there is no power led and even the serial connection shows nothing.

Is there anything I could try or is there some common hardware fault with this device?
I did not find anything else on the forum.

I also tried another power connector, which works fine with a second mir3g.