Thankfully Microsoft has since issued a statement on the matter. Apparently it seems that due to the size of the technical preview, the handsets were rejecting the recovery images that were being flashed onto their handsets. “The blocks of data were too large for some devices to handle, and the memory on the device was having trouble with the speed at which the data was being written. In short, devices were getting too much data, too quickly. This would cause the failure as the new software is corrupted.”
So what’s Microsoft going to do about it? “We will be lowering the size of the data blocks being fed to the device during recovery (lowering from 2MB down to 128kB), and we will also be slowing down the data writing speed (from 8MB/sec to 5 MB/sec). Testing has showed promising results from these changes.”
As for Lumia 52X owners who have bricked devices, it seems that the latest version of the Recovery Tool (version 1.2.4) has been released, so Microsoft is encouraging users to attempt to recover their handset using it.