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The fact that you missed updating your iOS 8 to iOS 8.0.1 and encountered errors that you can no longer use your phone normally, what we should do to completely fix it is only to downgrade back to iOS 8 and wait for Apple to fix the error.
The downgrade from iOS 8.0.1 is similar to you downgrading from iOS 8 to lower versions, here I will guide you in more detail.
Step 1 . Turn off “Find my iPhone” by going to Settings> iCloud
Step 2 . Download iOS 8 for iPhone 6 or iPhone 6 Plus, you get it here
Step 3 . Make sure you are on the latest version of iTunes.
Step 4 . Start iTunes on your Mac or PC.
Step 5 . Connect iPhone 6 or iPhone 6 Plus to iTunes via USB cable.
Step 6 . Click “Check for Update” and hold down the Option (Mac) or Shift (Windows) key on your keyboard. If done correctly, a window will appear for you to select the file to downgrade.
Step 7 . Select the iOS 8 Firmware (.ispw) file that you downloaded in step 2.
Step 8 . Click OK and wait for iTunes to start working
If you cannot disable the “Find my iPhone” function, you should put your iPhone 6 or iPhone 6 Plus into DFU mode and Restore with iTunes.
So taimienphi has instructed you to downgrade from iOS 8.0.1 broken device to iOS 8, we still have other updates from Apple hopefully will not disappoint again.
Image source: Internet
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