The CheckSUR log should be in the C:\Windows\Logs\CBS folder - If you haven't enabled viewing of file extensions for all files, then it will simply be call CheckSUR
If you can't find the Logs folder, you will need to enable viewing of Hidden Files and Folders.
In Windows Explorer (Computer), click on Organize, then Folder and Search Options
In the pop-up, click on the View tab, and put a 'blob' in the next to 'Show hidden files,folders, or drives'
You should also UNcheck the 'Hide file extensions for known file types' - Why MS keeps this as the default, I will never understand, as it confuses more people than almost anything I know!