Use a spudger to remove the CMOS battery from the board.

It is attached with a small amount of adhesive so you may need to pry it off, but be careful not to puncture or bend the battery.

Use a spudger to disconnect the CMOS battery connector cable from the motherboard.

To disconnect, use the point of a spudger to push on alternating sides of the connector to "walk" it out of its socket.

It may take a lot of alternating before the connector comes out. Be patient, and don't pull on the cables.

To reconnect the cable, align the connector and use a spudger or clean fingernail to push it fully into the socket.

Don't push on the cables themselves, or you may damage the connector.