problems with the lock button and power cable even after replacement.

I was looking at a phone that was having issues with the lock button sticking and not working. I have fixed this before on other phones with no problem (solutions from here that I have tried with success: unscrewing the bracket just a bit, taking the button out and making sure it's aligned correctly, replacing the button, replacing the cable). This has always been something I have had very few problems fixing. The old cable on this phone was missing the little plastic bit that helps push the contact point down and wasn't "springy" when i pushed it without the button on top so I replaced the cable. No matter which button I used, old or new (which really shouldn't make a difference they're all the same pieces of little metal but I have seen that suggestion on here before), it still wouldn't press down or even register at all. IF anyone has any ideas or solutions that would be amazing,

Thank you