Hello,
Please check with below articles.
Symantec Endpoint Protection 12.1 client install rolls back, returning 1603
http://www.symantec.com/docs/TECH170259
MainEngineThread is returning 1603 when uninstalling SEP 12.1 RU1 on Windows 7 and Windows XP machines 32 bit.
http://www.symantec.com/docs/TECH185779
SEPM installation rolls back.
http://www.symantec.com/docs/TECH104408
First, Check this Article:
Installer Information - "Symantec Endpoint Protection has detected that there are pending system changes that require a reboot." when trying to install SEP 11.0 on Windows 7
http://www.symantec.com/docs/TECH95608
Steps -
1. Open registry and go to
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\
hightlight Session Manager on the right hand side delete the value PendingFileRenameOperations
2. Also delete the same value from
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet001\Control\Session Manager\PendingFileRenameOperations
then run the install...without rebooting the PC
http://service1.symantec.com/SUPPORT/ent-security.nsf/ppfdocs/2007121609023348?Open&dtype=corp&src=&seg=&om=1&om_out=prod
Then
3.Disable UAC (Incase of Windows 7 and above)
4.If it's an upgrade uninstall SEP using cleanwipe utility and restart the system.
How to get the CleanWipe tool (Endpoint Removal)
https://www-secure.symantec.com/connect/forums/how-get-cleanwipe-tool-endpoint-removal
OR
4. Manually uninstall SEP.
Delete the contents of the SEP from the computer and registry after backing up the registry, then try reinstalling SEP.
http://www.symantec.com/docs/TECH184988
NOTE: For receiving CleanWipe utility requires you to create a case with Symantec.
In your case, I would recommend you to check this Article below:
Methods for uninstalling Symantec Endpoint Protection
https://www-secure.symantec.com/connect/forums/methods-uninstalling-symantec-endpoint-protection
Manual uninstall documents for Symantec Endpoint Protection
http://www.symantec.com/docs/TECH164769
http://www.symantec.com/business/support/index?page=content&id=TECH170259