Does your screen register random taps in that area?
My LS970 (the Sprint variant) gets a lot of these ?ghost touches" when plugged in via high-amp USB chargers.
If you want to change system-wide key functions instead of just what they do in the launcher, you can edit a file in /system/usr/keylayout. (On the LS970, the file to edit is keypad_8064.kl. This could be different for other variants but I'd imagine it's the same)
Open it up, unplug the battery, wait ~30s and plug it back in. pop the case back on and it will boot up fine. at least it did for me with the same sounding issue.