My z3 doesn't turn on unless I press the yellow button near sim is it a software issu

I had to change my phone's speaker in a local repair shop,after that the problem is persisting,power button is also functinal but not perfect. Is it a hardware issue???
I have an unlocked bootloader with RSXW 3, I tried factory reset in twrp & installing other rom, but haven't tried flashing a Ftf.
Please tell me how should i proceed???.:crying::crying:

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