Please can you help, this is the part i found of importance
MSI (s) (70:78) [11:43:39:194]: Running as a service.
MSI (s) (70:78) [11:43:39:209]: Opening per-machine managed SourceList.
MSI (s) (70:78) [11:43:39:209]: User will be allowed to modify contents of SourceList.
MSI (s) (70:78) [11:43:39:209]: Added new source 'C:\ProgramData\Symantec\Symantec Endpoint Protection\12.1.671.4971.105\Data\Cached Installs\' with index '2'
1: LinkAllExecutables 2: 0
MSI (s) (70:D8) [11:43:39:209]: Executing op: ActionStart(Name=StartServices,Description=Starting services,Template=Service: [1])
AddCacheAsInstallSource Successfully added C:\ProgramData\Symantec\Symantec Endpoint Protection\12.1.671.4971.105\Data\Cached Installs\ as source dir for {87C925D6-F6BF-4FBD-840B-53BAE2648B7B}
MSI (s) (70:D8) [11:43:39:209]: Executing op: ProgressTotal(Total=1,Type=1,ByteEquivalent=1300000)
MSI (s) (70:D8) [11:43:39:209]: Executing op: ServiceControl(,Name=SepMasterService,Action=1,Wait=1,)
MSI (s) (70:D8) [11:43:40:816]: Executing op: ActionStart(Name=ShowServiceProgress_RB,Description=Executing rollback script via service,Template=[1])
MSI (s) (70:D8) [11:43:40:816]: Executing op: CustomActionSchedule(Action=ShowServiceProgress_RB,ActionType=3329,Source=BinaryData,Target=ShowServiceProgress_RB,CustomActionData={DC2F6DF9-3CBC-4CAE-BCC2-466375BF8768};SOFTWARE\Symantec\Symantec Endpoint Protection;Executing rollback script via service;)
MSI (s) (70:D8) [11:43:40:816]: Executing op: ActionStart(Name=ShowServiceProgress,Description=Executing install script via service,Template=[1])
MSI (s) (70:D8) [11:43:40:816]: Executing op: CustomActionSchedule(Action=ShowServiceProgress,ActionType=3073,Source=BinaryData,Target=ShowServiceProgress,CustomActionData={DC2F6DF9-3CBC-4CAE-BCC2-466375BF8768};SOFTWARE\Symantec\Symantec Endpoint Protection;Executing install script via service;)
MSI (s) (70:8C) [11:43:40:816]: Invoking remote custom action. DLL: C:\Windows\Installer\MSI5266.tmp, Entrypoint: ShowServiceProgress
ScriptGen: ShowServiceProgress() MSIRUNMODE_SCHEDULED
ScriptGen: ShowServiceProgress() calling WaitForSingleObject(scriptStarted) ...
ScriptGen: ShowServiceProgress() WaitForSingleObject(scriptStarted) returned WAIT_OBJECT_0
ScriptGen: ShowServiceProgress() script execution failed.
ScriptGen: ShowServiceProgress() reset script failure event.
ScriptGen: ShowServiceProgress() is returning an error (so close to the end!)
CustomAction ShowServiceProgress returned actual error code 1603 (note this may not be 100% accurate if translation happened inside sandbox)
MSI (s) (70:D8) [11:44:23:467]: User policy value 'DisableRollback' is 0
MSI (s) (70:D8) [11:44:23:467]: Machine policy value 'DisableRollback' is 0
Action ended 11:44:23: InstallFinalize. Return value 3.
MSI (s) (70:D8) [11:44:23:467]: Executing op: Header(Signature=1397708873,Version=500,Timestamp=1100111219,LangId=1033,Platform=589824,ScriptType=2,ScriptMajorVersion=21,ScriptMinorVersion=4,ScriptAttributes=1)
MSI (s) (70:D8) [11:44:23:467]: Executing op: DialogInfo(Type=0,Argument=1033)
MSI (s) (70:D8) [11:44:23:467]: Executing op: DialogInfo(Type=1,Argument=Symantec Endpoint Protection)
MSI (s) (70:D8) [11:44:23:467]: Executing op: RollbackInfo(,RollbackAction=Rollback,RollbackDescription=Rolling back action:,RollbackTemplate=[1],CleanupAction=RollbackCleanup,CleanupDescription=Removing backup files,CleanupTemplate=File: [1])
MSI (s) (70:D8) [11:44:23:467]: Executing op: ActionStart(Name=ShowServiceProgress,Description=Executing install script via service,Template=[1])
MSI (s) (70:D8) [11:44:23:467]: Executing op: ProductInfo(ProductKey={87C925D6-F6BF-4FBD-840B-53BAE2648B7B},ProductName=Symantec Endpoint Protection,PackageName=Sep64.msi,Language=1033,Version=201392799,Assignment=1,ObsoleteArg=0,,,PackageCode={2FBA24A9-A366-4EBB-B6BA-5BE9A1E11E1E},,,InstanceType=0,LUASetting=0,RemoteURTInstalls=0,ProductDeploymentFlags=3)
MSI (s) (70:D8) [11:44:23:467]: Executing op: ActionStart(Name=ShowServiceProgress_RB,Description=Executing rollback script via service,Template=[1])
MSI (s) (70:D8) [11:44:23:467]: Executing op: CustomActionRollback(Action=ShowServiceProgress_RB,ActionType=3329,Source=BinaryData,Target=ShowServiceProgress_RB,CustomActionData={DC2F6DF9-3CBC-4CAE-BCC2-466375BF8768};SOFTWARE\Symantec\Symantec Endpoint Protection;Executing rollback script via service;)
MSI (s) (70:40) [11:44:23:467]: Invoking remote custom action. DLL: C:\Windows\Installer\MSIF901.tmp, Entrypoint: ShowServiceProgress_RB
ScriptGen: ShowServiceProgress_RB() MSIRUNMODE_ROLLBACK