There are four ways BLU update:
- Using recovery (to update installed OS)
- Using Fastboot (to recover BLU with Qualcomm SOC)
- Using Research Download (to recover BLU with Spreadtrum SOC)
- Using SP Flash Tool (to recover BLU with MTK SOC)
If you want to install a BLU update using recovery – download the official update, reboot your phone or tablet into recovery mode and click “Install update from SD card”.
To install BLU update with Fastboot – download and install drivers and ADB&Fastboot, download official firmware and flash it by instruction.