Power button is non responsive

I have a MacBook Air that stopped powering on. I opened up the back panel and disconnected the battery pack, reconnected the battery pack, and plugged the power adapter into it. Now my MacBook boots into the OS, but the power button is non responsive. If i shut it down I will not be able to get it powered up without running through the above steps. I don't want to do this everytime it dies, or gets shutdown.

The question I have is, will I need to replace the entire upper case to get the power button repaired, or is there just a power button with a ribbon cable/switch that can be replaced instead?

Any help would be greatly appreciated, thanks.