install packages
apt install gddrescue testdisk rsync kpartx dosfstools
gddrescue create an image of sdcard
ddrescue /dev/sdX rescueimage.img logfile
testdisk repair broken vfat
testdisk rescueimage.img
kpartx access disk image’s partition
kpartx -a -v rescueimage.img
fsck vfat
fsck.vfat /dev/mapper/loop1p1
mount
mount /dev/mapper/loop1p1 /mnt
Have fun!