After replacing CMOS battery what will you do?

Once the battery is replaced turn on the computer and resetting the CMOS values to the defaults. After the values have all been entered make sure to save the settings before exiting. Many CMOS setups allow you to press a key (such as F10) to save values and exit all in one action.

If after following all the above steps you continue to experience the same error when your computer starts or your computer is still unable to keep the stored values it's likely that you're experiencing a more serious issues. Most likely causes are bad power supply or bad motherboard.