iPhone 4s power button issue

i replaced the flex cable on my phone in order to fix the power button the othernight

when i rebuilt the phone the screen nolonger worked

for some reason i took the phone apart and rebuilt it again today and to my suprise when i plugged it into the pc to turn it on

the screen worked !!!

heres the issue:

the power button didnt seem to do anything,

it did however make the screen FLICKER

i made sure the button still clicks and the screws wasnt too tight

but ive no idea why it didnt do what it was suppose too ????

the annoying thing is shortly after the screens gone off again... i cant get it working

in the past since the power button was stuck i would usually hold the HOME button for a few seconds to get the screen to display but thats nolonger doing the trick

the backlight still works if thats an important detail

anybody got any advice for me please