There is a coin batter y inside the tough book. remove this and hold the power button in for 60 seconds to discharge the capacitors, the cmos memory should be cleared.

remove the RTC battery and the main battery, then unplug you computer and depress the power button for 30-60 seconds this should reset the cmos there are also posts locates at ic 61, 63 shorting these will perform a cmos reset as well.