Dell Inspiron 1521 Owner's Manual page 63

1 captive screws (2)
4. Disconnect the two antenna cables from the WWAN card.
1 antenna cable connectors (2)
5. Release the WWAN card by pushing the metal securing tabs toward the back of the computer until the card pops up slightly.
6. Lift the WWAN card out of its system board connector.
2 cover
2 WWAN card