iPhone 7 stuck on Apple logo

Hello there. My iPhone 7 is stuck on the Apple logo. Hard reset does not work, nor recovery mode or DFU mode or connecting it via iTunes and then restoring or updating the firmware. When i restore it via iTunes, it will give me the hello screen and tell me to set up the phone. Problem is, if a message pops-up the phone gets blocked and i have to hold the powerd button and do the set up process again. After that and the touchÍD, it tells me to add an icloud account, but then says that it cannot connect to Apple servers. As the message poped-up, the phone got blocked, had to turn it off and got stuck on the Apple logo again. I did the whole restoring and updating process 3 times. If i go to an Apple store(UK), how much will the repair be? Is it free? Do i need any type of documentation, such as phone contracts? And any suggestions on how to solve this?

NOTE: The system before updating was 11.2.2 but now it should be 11.2.6