Dell Latitude E6420 ATG (Early 2011) - Manual (Page 63)

10. Disconnect the modem cable from the modem card and remove it from the
system.
Installing the Modem Card
1. Connect the modem cable to the modem card on the system board.
2. Place the modem card in its slot in the computer.
3. Tighten the screw securing the modem card to the system.
4. Install the Keyboard Trim .
5. Install the Keyboard .
6. Install the Battery .
7. Follow the procedures in After working inside your computer .
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