The Real Time Clock (RTC) reset function allows you to recover Dell computer from No POST, No Power or, No Boot like situations. There is no coin-cell battery on this computer, the main battery reserves 2% of its capacity for RTC function.
How to Reset the Real-Time Clock (RTC)
Start the RTC reset with the computer powered off and connected to AC power.
Press and hold the power button for thirty (30-35) seconds.
The computer RTC Reset occurs after you release the power button.