If the phone is powered on and you can access the dialer, you may be able to toggle Diag Mode via the Engineer Menu. Open the app. Try the following codes: *#*#83781#*#* *#*#9646633#*#* Navigate to the Telephony or Connectivity tab. Look for "USB Setup" or "Port Settings."
Try a different USB port (preferably USB 2.0) or a different cable. Some modern USB 3.0/3.1 ports have timing issues with older SPD bootloaders. Conclusion enter diag mode spd
Connect the phone powered off while holding the boot key (usually Volume Down). If the phone is powered on and you
If you are working with a smartphone powered by a Spreadtrum (now Unisoc) chipset, you’ve likely encountered the need to enter (Diagnostic Mode). Whether you are trying to repair an IMEI, back up your NVRAM data, or perform deep system repairs using tools like Pandora, CM2, or Research Download, Diag Mode is the gateway you need. Look for "USB Setup" or "Port Settings
This is common with SPD devices. They often stay in Diag Mode for only a few seconds unless a service tool "grabs" the port. Make sure your software is ready and clicking "Connect" the moment the port appears. 2. Device Manager shows "Unknown Device"
Once granted root access, enter: setprop sys.usb.config diag,adb
Entering Diag Mode on a Spreadtrum device is the first step toward advanced mobile repair. While the method works for 80% of devices, knowing the Dialer Codes and ADB commands ensures you can handle any situation.