I don't think we directly move from 10 to 8.4.1.
First we need to downgrade to 9.3.5 and then we can try for 8.4.1.
So it will be two step process.
Initially u should download the version for installing and connect the mobile to the PC.
Then once the downloaded version done. then Click and hold on Power Button.
Itune pop up will be displayed. Then you able to see the Recovery mode and then restore on it and click on the new software downloaded.