The is widely known as a clone of the Ender 3 and typically uses firmware based on the Marlin 3D Printer Firmware . Because it uses an older 32-bit control board (often a clone of the SKR E3 Mini V2), you can find official and community-archived versions online. Official and Community Firmware Sources
This is the step most users forget. The Sunlu T3 has a separate microcontroller on the LCD screen (usually a DWIN or DACAI screen). If you update the mainboard firmware but not the screen firmware, you may see: sunlu t3 firmware
Run a PID Autotune. New firmware resets the PID values. The is widely known as a clone of