The firmware has a different SDSUPPORT buffer size. You need to use a smaller SD card (4GB or less) or reformat to FAT16. This is a limitation of the HAL driver Sunlu uses.
Invert the endstop logic. Open your firmware Configuration.h and look for X_MIN_ENDSTOP_INVERTING . Set it to false if it is true (or vice versa). You may need to recompile. sunlu t3 firmware
to eliminate the ghosting and artifacts that occur at high speeds, which the stock Marlin firmware cannot handle effectively. Official Updates: The firmware has a different SDSUPPORT buffer size
A frequent complaint regarding the is that after updating the mainboard, the screen shows blocks or garbled text. This happens because the screen (a DWIN set) has its own independent firmware that must match the mainboard's baud rate. Invert the endstop logic