Well, you aren't exactly supposed to reset the CMOS battery in a graphics card failure.
Try the graphics card in another computer and see whether it works. If it does, then its a motherboard issue on your part. As for openBVE, update to .NET 4, which linked above and try again. For a lot of modern computers, the CMOS battery just remembers the time and date, while BIOS settings are in a dedicated flash memory somewhere else on the board. Try to set the correct time and date in the BIOS, because some programs don't like conflicting dates (not exactly sure why, but GTAIV and WGA are pretty good examples of programs that don't like conflicting dates)