doesn't power on after screen replacement

Hi,

Today I replaced a iPhone 4s's screen, placed everything back as good as possible and I used gloves to take it apart and to reassemble. The problem is that (besides getting the backplate back on) I am not able to turn the iphone back on (or I cannot see anything, the assembly might be broken).

Do you know what might be the problem? Perhaps a drained battery (it is not mine and I do not have an iphone, so I do not really know anything about it)?

Thank you very much!

Pretty much seems like Powerbutton (on the top of the device) does not work. The iphone is currently turned on, but I am not able to shut down (or do I need to enter the code for that?). Also it keeps searching for networks (perhaps I need to enter the code for that too?).

Edit: I separated all the parts of the phone and I found the Power-button cable stuck under the logicboard. Reattached and it works now(: