In general, they will be stored in %UserProfile%\AppData\Local\Temp.
2. Locate the component that failed.
The very first log in the chain is an overview of the installation process and primarily can be used for letting you know which component failed to install.
Error 0x80070643: Failed to install MSI package. Error 0x80070643: Failed to execute MSI package. Error 0x80070643: Failed to configure per-machine MSI package. Detected failing msi: ServiceDispatcher Applied execute package: ServiceDispatcher, result: 0x80070643, restart: None Error 0x80070643: Failed to execute MSI package. ProgressTypeMajorUpgrade Starting rollback execution of ServiceDispatcher
3. Locate the error in the component log file
Installation logs are generally long. To locate where the process failed, search for Return value 3. The content above this line indicates where the installation failed. Use the error printed to further investigate the failure.