The user can choose what to do if the gets stuck in the finalizing phase. Reason can be that the factory reset is taking a long time or the device does not report the end of factory reset to Blancco 5 Mobile.

In this case, the device goes to "Requires attention" state with the following options:

If the above mentioned options are not available, try enabling USB debugging on the device. After a while the device should appear as 'Erased".