@Harold This is odd. You’ve to know that BATOCERA exits of 2 partitions. One is FAT32 and there is the image container of the system resided (see it as container with all data filled), the second partition is the usershare and from there you should have 29GB of free space available. You may try to reformat within EmulationStation menu … you can also try to reenable the auto expand of the partition by setting up
/boot/batocera-boot.con and enable the autoresize switch again.
Use the command
batocera-es-swissknife --remount command to enable write access to /boot partition.