Correcting French Characters in MySQL
UPDATE tbl
    SET col = REPLACE(col, 'É', 'é') COLLATE utf8_bin;


I don't know if the COLLATE clause is needed at all.
If col is not CHARACTER SET utf8, then use the appropriate "_bin" collation.
Test before applying:

SELECT col, REPLACE(col, 'É', 'é')
    FROM tbl
    WHERE col LIKE '%É%'
    LIMIT 22;