For users with Lumia 520/521 devices that have become unusable after an attempted recovery using the
Windows Phone Recovery Tool (WPRT):
We have been gathering your feedback and actively researching the situation. We have important updates to share:
Devices that have failed to recover appear to fall into one of two different states:
- Displaying a red Nokia logo
- Displaying a black screen and the device is non-responsive after attempting to boot.
Although our investigation is not complete, we’d like to share some initial insight into what we’ve uncovered:
Data writing size & speed: It was discovered that some devices are having trouble accepting the recovery image data being flashed. 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.
Small portion of 520/521 devices affected: As we reviewed logs and worked through issue reproduction, we identified the subset of affected 520/521 devices that may encounter this issue. There is no direct way for an end-user to check their device unfortunately, however it is positive news that not all units would experience this issue..
As a result of these findings, we are making two key changes to the way the recovery tool (WPRT) works. 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.
To implement these changes, we have released an updated version of the WPRT tool. You may notice when launching the WPRT that it checks for updates automatically. Before attempting any further recovery or flashing on 520/521 devices, ensure that you’ve closed and re-launched the WPRT. It will find this new mandatory version and automatically update.
Before we re-enable the update path from WP8 to Windows 10 Technical Preview for these devices, we will be reaching out to users to do a bit of additional real-world testing. Once we’re confident in the results, we’ll turn the update path back on for these devices.
User Expectations & Recovery efforts:
For users who have already unusable devices, we’re continuing to research this situation. There is no guarantee that using this updated version of the tool will recover an already-bricked device. If your device is showing the red Nokia logo, please do the following:
- Ensure your device has a good power source (connected via USB cable that can transfer data and charge the device simultaneously)
- Close the WPRT, re-open, and take the update to the new version of the WPRT. The new version is 1.2.4
- Once he new version is installed, re-attempt the flashing process.
- If your device is not recognized, click the "My phone was not detected" button and continue the attempted recovery process
Please check back for additional details and updates. More information will be shared as it becomes available.