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Hi there and welcome
Can you please hold the power button until a menu shows and choose power off.
Then remove the Sim card and rub it on your sleeve.
Add the sim card back into the phone, power it on and tell me if it now functions correctly.
Do you have another phone there available?
ok there are 3 causes left for this, a corrupted firmware, faulty sim card or faulty sim card port on the actual phone itself.
The only thing we can now rule out here is the firmware and to do this we need to do a full reset of the phone
This will remove all data from the phone and return it to new, but you cannot avoid this so backup your data first please.
Once done, go to settings, backup and reset, factory reset
Let this complete, set up the phone again and tell me if it then functions correctly