def handshake(dev): # Send two dummy packets to reset preloader state dev.write(b'\xff\xff\xff\xff\xff\xff\xff\xff') time.sleep(0.02) dev.write(b'\x00\x00\x00\x00\x00\x00\x00\x00') time.sleep(0.05) ack = dev.read(1) # Newer chips respond with 0xA5 after a delay, but sometimes 0x5A first if ack == b'\x5a': time.sleep(0.03) ack = dev.read(1) # second byte is 0xA5 if ack != b'\xa5': raise HandshakeError(f"Expected 0xA5, got {ack.hex()}") He saved the script as mtk_bypass_fixed.py , ran it with admin privileges, and held down the volume buttons as he plugged the phone in.

He leaned back, running a hand through his hair. The phone—a bricked Infinix Hot 10—sat lifeless, its boot loop mocking him. All because he’d tried flashing a custom recovery without unlocking the bootloader properly. Now, the MediaTek preloader was stuck in a handshake war with his laptop.

Arjun grabbed the Python source of the bypass tool. He traced the handshake function:

It was 11:47 PM when Arjun’s screen flickered with the dreaded red text:

“Not again,” he muttered. Two hours earlier, things had seemed simple. His friend’s phone had the infamous “DA (Download Agent) mismatch” after a failed OTA update. Arjun had used the MTK Bypass Tool before—it exploited the brom (bootrom) mode before security patches killed the vulnerability. But this time, the phone’s firmware was newer. The handshake protocol expected a specific response from the preloader, and the tool’s patched libusb wasn’t aligning.

Every attempt ended the same:

The terminal output changed:

Handshaking error: resolved. Not by luck, but by reading the silence between the bytes.

He saved the modified script, wrote a quick README, and posted it on GitHub at 2:14 AM.