Windows batch script to change the string on multiple files

@echo off
setlocal EnableExtensions DisableDelayedExpansion

set "search=OLDSTRING"
set "replace=NEWSTRING"

set "textFile=*.bch"
set "rootDir=."

for %%j in ("%rootDir%\%textFile%") do (
    For /F "Tokens=1*Delims=]" %%A In ('Find /V /N ""^<"%%~j"^&Break^>"%%~j"'
)Do (Set "line=%%B"
    SetLocal EnableDelayedExpansion
    (If Not "%%B"=="" (Echo(!line:%search%=%replace%!)Else Echo()>>"%%~j"
    EndLocal)
)

endlocal