Unable to unlock SIM

After replacing the rear cover, the dock port and the battery, impossible to unlock SIM card.

The phone opens normally but at unlocking the SIM by code and pressing OK, the phone replies "unlocking please wait" and nothing else happens and the phone shuts on stand-by.

Is it the SIM connectors that are ruined?

Is the logic board ruined?

In case of Sim connectors, are there any guides to replace them?

In case of logic board failure, can you provide one?

Thanks in advance

Denis Gaille

Athens Greece