If you have decided you’d like to update an iPhone or iPad to iOS 9, you can install iOS 9.0.1 manually using firmware and iTunes. The manual firmware method is more advanced, making it perhaps best for specific reasons, like to resolve the frustratingly unresponsive “Slide to Upgrade” screen, to fix the Software Update Failed error, due to storage space limitations on the target device, because sometimes it’s just easier due to bandwidth constraints, or because you’re updating multiple of the same devices. Whatever the case, we’ll walk you through the entire process.