Galaxy S5 Recents Button Replacement

I just bought an used galaxy S5 active. However, the recents button is non-responsive. All the other buttons work fine, it is only the recents that I can click but it does not respond. I tried opening the device but I do not know if replacing the button connectors for brand new ones would help, or how to even get behind the plastic rims and into that part of the phone. Any help would be appreciated,

Thanks!