Zte Mu5001 Firmware — __top__

Yes, but only if the bootloader version is the same. If you upgrade from B09 to B12, you cannot revert to B09 because the anti-rollback fuse (efuse) is blown. Check your device: adb shell getprop ro.boot.anti_rollback .

Yes, using QPST (Qualcomm Product Support Tool). You must root the device first (requires a modified bootloader). Not recommended for casual users. Zte Mu5001 Firmware