I would first try to reset the RTC:[br]
Turn off the computer.
# Connect the AC adapter to the computer.
# Press and hold the power button (around 30-35 seconds), until the power LED blinks three times.
# Release the power button.
# The RTC reset is complete after the power button is released.
Otherwise, are there any error codes? Does the power indicator light blink any sequence of orange/white?