Can't disable "Find my iPhone"
My iPhone 8 does not turns on, the apple icon appears and reboots again. Also there is a problem with battery. But in service center told me to disconnect from the "Find iPhone" first. In another iPhone were my apple id is logged in, instead of disconnecting from "Find iPhone" in iCloud I mistakenly removed it from the list of iPhones in the settings, so now it is not displayed in the iCloud ... I just don't know what to do.
iPhone 8