My iphone 5c won't finish the new update. Any ideas what i could do?

Odds are there is not enough storage on you iPhone 5c so it won't update.

Get help with over-the-air iOS updates - Apple Support

Hope this helps, best of luck to you.

Go to Settings > General > Storage & iCloud Usage > Manage Storage (the first one) > and if there is an update listed, delete it. Then restart, go to Settings > General > Software Update and try downloading the update again.

If this does not help try updating through iTunes on your computer.