Invalid Sim Card Network Locked. Go to mobile networks in settings and then click the network operators option. Have you tried a factory reset?
When the reason for “invalid sim card. Entering the an incorrect sim network unlock pin results in a phone then asking for the sim network unlock puk. Quick googling reveals that these notifications and errors typically show that a phone is locked to a specific carrier.
Follow the instructions from the instruction file.
The “network locked” part of the message indicates that the phone is still locked. When the reason for “invalid sim card. Side notes regarding that might be helpful. Tell them the exact message displayed by the phone.