Ok, I'm
stupid or forgetful or I just have too many consoles.
Since I used only one AES all the time, I completely forgot about the other power adapter. I just used the wrong one, 10V instead of 5V. Guess I'm lucky nothing blowed up.
With the correct adapter, everything works fine.
Thanks ApolloBoy, your post helped me to search for another power adapter.
Thanks Tyranix95, this info might be useful for the future or other repair questions. I was already in contact with Xian Xi, but I'm from the other side of the world (Switzerland). MKL is pretty close, but has turned off PMs (for whatever reason).