If you receive Update error 80070490, it means that a file (CBS Manifest) that's needed to install updates is corrupt.
Run the System Update Readiness Tool, follow these steps:
Swipe in from the right edge of the screen, and then tap Search. (If you're using a mouse, point to the upper-right corner of the screen, move the mouse pointer down, and then click Search.)
Type command prompt in the search box.
In the list of results, swipe down on or right-click Command Prompt, and then tap or click Run as administrator.
In the Administrator: Command Prompt window, type the following commands exactly as they appear. Press the Enter key after each command:
DISM.exe /Online /Cleanup-image /Scanhealth
DISM.exe /Online /Cleanup-image /Restorehealth
To close the Administrator: Command prompt window, type Exit, and then press Enter.
Run Update again.