getting syntax error when trying to run ren command

I am trying to build my software using cx_freeze for which I built a bat file that runs the build command so when the build is completed it generates build directory inside which there is another directory exe.win-amd64-3.6 containing the bundled code. inside which there is lib/scipy/spatial/cKDTree.cp36-win_amd64.pyd now this file has to be renamed as ckdtree.cp36-win_amd64.pyd for the build to run. I am trying to automate this by including rename in batch file but it's giving error.

I am trying to run rename command when build is completed but it's not working i get the error the syntax is incorrect. i tried to remove

%~dp0  

even this didn't work

@ECHO OFF
Set "FRAS_Folder=%~dp0build_logs\FRAS"
If Not Exist "%FRAS_Folder%" MD "%FRAS_Folder%"
Call :Gen_Report_Name fras_logname
echo FileName : "%fras_logname%"
echo Absolute PathName : "%FRAS_Folder%\%fras_logname%"
REM Example save the result of this command with a log file into this folder
python setup.py build>"%FRAS_Folder%\%fras_logname%"
@REM rename the scipy.spatial.cKDtree file to scipy.spatial.ckdtree in lib/scipy/spatial
@REM rename the file cKDTree.cp36-win_amd64.pyd to ckdtree.cp36-win_amd64.pyd in lib/scipy/spatial
ren "%~dp0build\exe.win-amd64-3.6\lib\scipy\spatial\cKDTree.cp36-win_amd64.pyd" "%~dp0build\exe.win-amd64-3.6\lib\scipy\spatial\ckdtree.cp36-win_amd64.pyd"


pause & exit /b

:::::::::::::::::: FUNCTION :::::::::::::::::::
:Gen_Report_Name <file_with_date to be set>
for /f "delims=" %%a in ('wmic OS Get localdatetime  ^| find "."') do set "dt=%%a"
set datestamp=%dt:~0,8%
set timestamp=%dt:~8,6%
set YYYY=%dt:~0,4%
set MM=%dt:~4,2%
set DD=%dt:~6,2%
set HH=%dt:~8,2%
set Min=%dt:~10,2%
set Sec=%dt:~12,2%
set "stamp=%YYYY%%MM%%DD%_%HH%%Min%%Sec%"
Set "%1=%stamp%.log"
Exit /b
::------------------------------------------------------------------------------------

Kindly help me figure what's the issue!

You are using the wrong syntax for the ren command. See ren /?
The second filename must be a filename without path.
If you prefer to include the path for the second filename use the move command.

Windows is case insensitive so the files are having the same name. You will need to use an intermediate filename to change the case of the filename.

Try this:

ren "%~dp0build\exe.win-amd64-3.6\lib\scipy\spatial\cKDTree.cp36-win_amd64.pyd"  "%~dp0build\exe.win-amd64-3.6\lib\scipy\spatial\ckdtree.cp36-win_amd64.tmp"
ren "%~dp0build\exe.win-amd64-3.6\lib\scipy\spatial\ckdtree.cp36-win_amd64.tmp"  "%~dp0build\exe.win-amd64-3.6\lib\scipy\spatial\ckdtree.cp36-win_amd64.pyd"