1600 nokia phone insert sim problem

At the bottom of the phone you have the headset, charging and easy flash (USB) connectors. If the easy flash (USB) connector is soiled, oxidized, dirty or the terminals are shorted; it can cause the sim card issue. The unit starts and takes long to display then "insert sim card" appears.
To resolve the issue:

1. Clean the easy flash connector with a lacquer thinner or even a 70% ethyl alcohol.
2. Make sure dirt is removed between the terminals.
3. If you can disassemble the unit, clean the connectors terminals from inside.
4. Clean also the board.

To disassemble the unit:

1. Remove A and B-covers.
2. Remove the six T6 screws.
3. Pry the board including the LCD frame and light guide assembly from the sides to remove it from the D-cover.
4. Reassemble in reverse order.