Start With
If you can't download the update package or the download doesn't
go beyond 0%, try clearing the System update cache.
Follow these steps
Step 1
Go to Settings, 
open Apps Notifications and select Apps.
open Apps Notifications and select Apps.
Step 2
Select System Update, Storage and then tap Clear
Data and Clear Cache.
Step 3
After the data cache is deleted, try again to update the
device by going to Settings, System and then System update.
Done