Mac Mini only starts after plugging out and in PRAM battery

Hi,

The power button apparently has no function anymore. I can since then only can start my Mac Mini from late 2014 by plugging out the CR2032 PRAM battery and plugging it back in.

Curiously, the starting of the boot process including the chime sound occurs after plugging the power cable and not pressing the Power On button.

Another thing is, that I only can restart the system, when the SSD internal drive has not been connected to the logic board. So, if I plug out and in the Same battery or even plug in a new PRAM battery and at the same time I connect the internal Hard drive to the board, I am able to start only once. When I do not Connect the Hard drive, I can start the system inifinite times but without pressing the Power On button.

The Power On Button seems to have no damage and it is still connected to the board with two wires.

Can anyone help me? There is an 8pin BIOS related device right in front of the L-wise formed black unit.

Has it anything to do with that. In another topic, someone heated up the logic board to 180 centigrade degrees 15 minutes long and could get rid of an issue.

Do you think, this May help me?

Thanks