Sounds like you have one or a combination of stuck buttons.
The steering wheel controls are quite simple in operation. Instead of multiple outputs, there is only 1 output...a variable resistance to the headunit. The headunit reads the resistance, looks up the resistance table programmed into it, and executes the command based on the resistance that was read.
In this case, the toothpick mod wont work. The button switch is internally shot, so you would either have to replace all the buttons (hey you might as well if you gotta tear into it) or find a junkyard replacement. Even then, there are no guarantees.
Welcome, downwardly mobile yuppies, to the dawn of the Age of Nefarious.
1993 SSEi - FrankenJinx - dead and gone.
1994 SSE (136K strong) - 180* t-stat,HD alternator, most unequipped SSE on the club, XM radio, Kenwood CD/MP3.
2006 Chevy Malibu Maxx LTZ - Custom 2.25" manifold-back exhaust w/FM-80. Probably the only Maxx with this system.