my iphone is blocked by a scammer

hello, I am writing to you from the city of Nur-Sultan. On January 12, 22, I posted an ad that I want to sell the phone, in olx. one girl named Madina (it says so in WhatsApp) writes from WhatsApp that she wants to buy my phone, but wants to check if her iCloud will fit my phone. she sent her data, username and password icloud. I logged out of my account and entered her username and icloud password. and writes me a letter that within 15 minutes send 15,000 tenge, if I do not send tomorrow this amount will increase. At that moment, my phone was blocked. because she managed to quickly change her password. at the moment, he also threatens, demanding money. and my iPhone is still locked up. the screen says this phone is gone, write to this number. I turn to you for help. I hope you give feedback, thanks in advance