Unlocking the bootloader is the first step to installing custom software. However, the ZTE Blade A51's UNISOC chipset doesn't use the standard fastboot oem unlock command. Instead, unlocking requires specialized methods and tools. Recent developments have leveraged an exploit like , with community tools using it to unlock the bootloader on this and similar devices. These methods often require using a tool to put the phone into a special SPRD (Spreadtrum) EDL mode . Be aware that unlocking the bootloader is a risky process; proceed with caution.
For standard software updates that do not require a full system wipe, the ZTE Blade A51 supports Over-the-Air (OTA) updates. This can be accessed via . If an update package is available, the device will download and install it automatically. Firmware ZTE Blade A51