What to do if the physical SIM card shows invalid or unregistered?

Check if the installation direction is correct. Remove and reinsert the SIM card according to the slot markings.

Clean the SIM card chip (gently wipe with a clean soft cloth to remove dirt or oxide layers).

Try replacing with another card slot (if the device supports dual SIM).

Restart the device and recheck recognition.

If still not recognized, the SIM card may be damaged.