Okay, here's the simple script if you want to change uppercase filenames to lower-case & vice-versa.

Uppercase Filenames To Lowercase :

#!/bin/sh
if [ $# -eq 0 ] ; then
echo Usage: $0 Files
exit 0
fi
for f in $* ; do
g=`echo $f | tr "[A-Z]" "[a-z]"`
echo mv -i $f $g
mv -i $f $g
done

Lowecase Filenames To Uppercase :

#!/bin/sh
if [ $# -eq 0 ] ; then
echo Usage: $0 Files
exit 0
fi
for f in $* ; do
g= `echo $f | tr "[a-z]" "[A-Z]"`
echo mv -i $f $g
mv -i $f $g
done

make both scripts executable & make your life easy 👍