Hello,
Could you please Upload the SEP_Inst.log which could be located on START > RUN > %temp%
Also, Check the permission on C:\Programdata (program data is hidden folder)
delete c:\program files(86)\symantec
c:\program files(86)\Symantec Endpoint Protection
c:\ProgramData\Symantec
MAKE SURE UAC IS OFF
Reboot you machine then try installing SEP again from C:\Temp\clt-inst\setup.exe
Hope that helps!!