Dear Bob McDermott,
Thank you for sharing the details about your Surface Pro 8.1 being stuck on the BitLocker recovery screen. BitLocker requests the recovery key when it detects a change in hardware or system configuration. The recovery key is stored in the Microsoft account associated with the device, or it may have been saved to a USB drive, printed copy, or within your organization’s Active Directory if managed by IT. Please sign in to https://account.microsoft.com/devices and check under “BitLocker recovery keys” to locate the key. Once the key is entered, the device should unlock and allow access to Windows. If the recovery key cannot be found, contacting Microsoft Support with proof of ownership is the recommended next step.
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Best regards,
QQ.