Hello Douglas Hanson,
The “Welcome to AEG” screen indicates that the Surface is likely still registered to AEG through Windows Autopilot. Autopilot identifies the device online by its hardware identity, so deleting partitions, reinstalling Windows, using a Surface recovery image, or erasing the drive will not remove that registration.
For reference, Surface UEFI is opened by shutting down the device, holding Volume Up, and pressing and releasing Power. However, there is no UEFI setting that can remove an Autopilot registration.
The reseller needs to have the Surface removed from the previous organization’s Windows Autopilot tenant. Please contact the reseller and request that the device be properly deregistered. Microsoft also documents a Surface Autopilot deregistration process, but it requires valid proof of ownership, including an original invoice containing the device serial number.
If the reseller cannot arrange deregistration or provide the required ownership documentation, the practical option is to return the Surface for a refund or replacement. The device was not properly released from organizational management before resale.