All of the basic settings on your Compaq Presario C700 laptop are stored with power from a tiny battery about the size and shape of a watch battery. When that battery begins to fail, you may notice that the clock on the C700 starts to lose time, or that the unit resets its memory count every time it reboots. If you notice any of these symptoms, replacing the CMOS battery, also known as the RTC battery, on the system board should resolve them. The process requires care and attention to detail.
Shut down the laptop and remove the power cord from the back. Turn the C700 over so the bottom is facing you. Slide the battery release lever to the unlocked position and lift it out of the laptop.
Remove the screws holding the hard drive in place. Grasp the drive by its front bezel and pull it out of the case. Do the same with the optical drive.
Locate the three Phillips head screws that secure the keyboard to the C700. These screws are on the bottom of the laptop case. Set the screws aside and turn the laptop right side up.
Open the laptop as far as it will go, then gently lift up the back edge of the keyboard with a small flat head screwdriver or similar instrument. Carefully pry the keyboard up, then lift it off the case and lay it over the display panel.
Turn the computer upside down and remove the line of screws along the back side of the unit. Turn the laptop right side up and open it as far as it will go. Remove the power button cover and switch cover and set them aside.
Disconnect the display panel cable and pull it through the routing channel on the top panel of the laptop. Remove the microphone cable from the C700 system board.
Remove the screws that hold the display panel to the laptop. Lift the display panel off and set it aside.
Turn the computer upside down with the front of the laptop toward you. Locate the Phillips head screws that secure the front panel to the unit. Remove those screws, then turn the laptop right side up.
Disconnect the LED cable and touch pad cable from the system board. Lift the rear edge of the top cover and swing it up and toward you. Lift the top cover off the laptop.
Remove the power connector from the system board and run it through the routing channel. Remove the Phillips head screws that secure the system board, then remove the USB board cable.
Grasp the edges of the laptop firmly and flex them back and forth to loosen the system board. Lift up the right side of the system board and pull it up at an angle.
Turn the system board upside down and disconnect the CMOS battery. Insert a new CMOS battery and connect it to the system board. Reverse the preceding steps to reassemble the laptop.
The replacement battery for the C700 is part number 454947-001, according to the laptop manual.