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After update 50.2.A.0.352
Phone doesn't see two Sim cards simultaneously. When two Sim cards in cardholder - message appear "No cards - No connection. And phone doesn't unlock. Working only first or second card.
Hi @Oleh_H, I am sorry to hear about this, do you get the same error message if only one SIM card is inserted?
Firstly, have you checked whether the SIM cards are mounted correctly in the device. Please view this link for instructions on how to insert two SIM cards correctly.
Secondly it is a good idea to check how old your SIM card is. Previous SIM card formats used different voltages i.e if your card is older than 4-5 years please contact your network operator to swap your SIM card. Another good idea is to test other SIM cards in the phone, as as different devices might react differently to a possible defect of a SIM card.
Try these measures and let me know how it goes!
Hi, Martin.
Problem was in one of card. Card was blocked, I don't know why it block both of card slots. I solved this problem. Now it's working fine.
Thanks.
Hi @Oleh_H and thank you for your quick response!
I am delighted to hear that you have managed to solve it and that it was something so minor as a change of SIM card that was needed! 
Feel free to get back to me if you have any other questions regarding your phone! 