Troubleshooting failed upgrade to Windows 7?

Might be some useful logs files you can see.

Then I found the file C:\$Windows.~BT\Sources\Rollback\setupact.err had some useful info.

Details here.

Many times, the errors present in setuperr.log/setupact.log may be a red herring. Even upgrades that complete successfully include such errors. What frequently happens in these upgrades that automatically roll back to the original OS is that some "out-of-box" device driver is blue-screening the system when it boots into the new OS for the first time. In such cases, there may be a dump file left behind after the upgrade rolls back; see #36402 for more details.

1. Open up Run box and open MSCONFIG.

2. Click on Services Tab and Hide Microsoft Services.

3. Disable all the services on the list. Same thing with all startup items.

4. Open CMD with elevated privileges.

5. Type net user Administrator password and press Enter. It will say command completed successfully.

6. Type net user Administrator /active:yes and press Enter. Again it will say command completed successfully.

7. Restart the computer and then log in under the Administrator account with the password as password.

8. Start the Windows 7 Upgrade again, this time it will finish.

I have tried it on four computers with the same problem that would not install Windows 7 Upgrade from Vista SP2.