Well, if you turned off your PSU and your CMOS reset, then it is possible that your CMOS battery is dead. It could also be a clever feature of your mobo. Some mobos will reset the BIOS to factory defaults when it senses that you have made a bad overclock config, and knows that it is so bad that it cant properly boot.
As for the button not working, I am not sure. I would try making a simple change in CMOS (like the boot order), then shutting down and pressing the CMOS reset button. Then go back into CMOS setup and see if that changed it back to the original settings. If it turns out that it doesnt reset the CMOS, then, I suppose you could send the mobo back, depending on your warrenty, etc.
Intel E6750...........PSN: ELBATROP
XFX nForce 650i Ultra
Patriot PC2-6400 8GB (4x2GB)
36GB WD Raptor
Samsung SyncMaster 931c
Samsung SyncMaster 750s
Windows 7 Home Premium 64