To fix the "Can't open _dsmenu.dat" error, ensure that the files "_DSMENU.DAT" and "_DS_MENU.DAT" along with the "_rpg" folder are in the root directory of your micro SD card, not inside any folders. Often, these files end up in a folder (like "r4_kernel") when extracting the kernel files. Move them from the folder to the main directory of the micro SD card to resolve the issue.

To fix the "SD/TF card error" error, reformat the micro SD card to FAT32 using a full format (not Quick Format) to check for any bad sectors. For stability, use a micro SD card with a capacity of 32GB or lower and a speed rating of Class 10 or higher. After formatting, reload the kernel files directly to the root directory of the micro SD card.