This is almost always a driver issue. Reinstall the SPD Drivers and restart your PC.
While continuing to hold the key, plug the USB cable from the PC into the device. enter diag mode spd
This usually means the phone is not entering the correct pre-boot state. This is almost always a driver issue
Tools like SPD Upgrade Tool , Pandora Box , CM2 (Infinity-Box) , or UnlockTool are commonly used to interact with this mode. Method 1: The Hardware Button Combo (Most Common) This usually means the phone is not entering
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If the phone is stuck in a boot loop but can be recognized by a PC: Connect the phone to a PC. Ensure ADB drivers are installed. Open Command Prompt/Terminal and type: adb shell su setprop sys.usb.config diag,adb Use code with caution. This command forces the USB configuration to swap to DIAG. How to Verify Diag Mode is Active
Windows will immediately play a hardware connection sound and load the diagnostic port interface in Device Manager. Method 3: Using Servicing Dongles and Specialized Tools