Running a wideband constantly won't do anything to it, many vehicles run widebands from the factory. They're much higher quality than narrowband sensors, but are more fragile and less tolerant of abuse or misuse.

It's a wideband gauge with an integrated wideband controller I'm assuming? There is a lot that can go wrong, That's not a simple PiC microcontroller-based cheapie narrowband gauge. There are current references, a controller chip, a differential amplifier, and then there are the display parts. Much more built in than a narrowband gauge that just reads O2 voltage.

It sounds like a ground problem, the current source for the O2 sensor can easily be damaged if the unit is grounded through the sensor body (or not at all) instead of being grounded through the gauges' chassis ground. You've probably damaged the gauge; the O2 sensors aren't that fragile themselves but who knows what might happen in an improper grounding situation.

Is the gauge not lighting up, or is it not displaying a sensible reading? There are a few things that can go wrong with the gauge..