If the dialer codes do not work, or if you are a technician, use ADB commands. This requires to be enabled in Developer Options.
When an Android phone boots into its standard operating system, its USB port behaves as an MTP (Media Transfer Protocol) device or an ADB debugging interface. Entering changes the USB configuration, forcing Windows to recognize the hardware as a functional COM Port (typically labeled as SCI General U2S or SPRD U2S Diag) . Technicians use this interface to:
Hardware dongles provide the most reliable method for newer UNISOC and legacy Spreadtrum security patches. enter diag mode spd
Ensure the volume buttons are fully functional. If the buttons work, your device may have an locked bootloader that blocks standard hardware commands. In this scenario, you must utilize an advanced service box that supports a hardware test-point connection to ground the KCOLO / Boot Pin directly on the motherboard.
Ensure your battery has at least 30% charge. Low voltage can cause the Diag port to be unstable. If the dialer codes do not work, or
on some routers/switches:
SPD diag mode active. Checking surge counters... Entering changes the USB configuration, forcing Windows to
For Spreadtrum/UNISOC devices, there isn't a single universal command, but these are the most standard methods: Dialer Codes : Try entering codes like *#*#83781#*#* *#*#9646633#*#*