Pretty sure my switch needs replacing. Any troubleshooting steps I should try that I have not thought of?

The factory reset / Z-Wave replace will work perfectly with the child device. There seems to be a driver matching bug with HE right now so it might possibly switch to the system driver when you pair but it should not mess with the child, just switch back to my driver if it does that.

*Take a backup before also, just in case something goes wrong you can at least restore the device entry / automations.