Modern Tecno devices, including the BD3, employ advanced security mechanisms like and DA Authentication . The factory DA file is signed with a specific cryptographic key. If you use a generic DA (from SP Flash Tool’s default MTK_AllInOne_DA.bin ), the phone will reject the handshake, resulting in the dreaded "DA mismatch" or "DRAM setup failed" error. This is why the device-specific Tecno BD3 DA file is non-negotiable.