Dell OptiPlex 3000TC Service Manual page 29

Steps
1. Insert the coin cell battery into the coin-cell battery slot on the system board with the "+" sign facing up.
2. Slide the coin-cell battery under the securing tabs at the positive side of the connector.
3. Press the coin-cell battery into the coin-cell battery slot until it locks into place.
Results
To install the mylar sheet, follow the below mentioned steps:
The coin-cell battery has a black mylar for cosmetic purpose only, not function impact. During the installation of a new system
board, it is recommended to transfer the black mylar from the previous system board to the new system board.
1. Use the folding lines on the mylar sheet to fold the mylar.
2. Insert the mylar under the RTC socket.
3. Using the finger, tap and hold the mylar sheet. Insert it under another side of the RTC socket.
Next steps
1. Install the side cover.
Removing and installing components 29