No lights on the hard buttons--> external speaker fails -->micro fails

Hi guys,

you are my last hope !

The problems with my lumia 1520 began with the missing light of the back button, continued with missing light of the windows button, followed by fails of the external speaker in noise and loudness and ends up until now with not working microphone.

The phenomenon is that if I bend the 1520 by pushing on the upper left and the lower right corner and holding it in the middle of the back side, the lights of the windows and back button are working as well as the external speaker. So i guess the 1520 has a internal contact problem, caused by transporting it in the trouser pocket.

I just try to bend it the other way round but no effort so far. Would it be helpfull to diassemble the lumia 1520 and reassemble it again to fix the internal contact problems ? (it's only my root cause no idea if i'm right)

I very appreciate every type of help or answer.

Thanks in advance