Unfortunatelly the second method hasn't worked, too.
Also the method to check if the mobile is still alive failed. It looks like it is absolutely out of order. And I was not flashing the device recently.
I guess there is no other option but send it to be repaired again.

Hello, I can't switch on my phone. I was following your advices - trying to switch on useing two methods you are writing about. "sorry to hear that. There would be two ways that I can suggest. First of all, keep the ON/OFF button pressed for 20-25 seconds while connected via USB cable to your P...