Galaxy S5 Mini

Before buying can indeed any information about the technical strengths and weaknesses.
For this I now want to also do not write anything.

In principle and was with the phone (still) everything ok.
Last but piling up the problems:

Once the battery at 100% starts the power supply to a very high frequency sound to deliver.
As I invite the unit overnight bed next to the pillow that's very unpleasant.
This effect occurs almost always.

Lately accumulates the phenomenon that the unit is suddenly easy out.
Very strange ...

2 months I have it now.
I'll be watching the whole thing for a while and try to figure out what it could be - if this
is not possible but I will return it to Amazon.

If anyone knows the problem and a solution has the ready - just tell me.