Let's get this sorted for you. Let's try a soft reset on the phone. Press and hold the 'Power' key, and the 'Volume Down' key simultaneously, to see if the phone will power off and then reboot.
@julie barnett: Can you try connecting the phone to your charger, either via a plug adapter or USB cable in your home computer, to ensure that the device has sufficient charge. If it does, and if the phone continues to hang on the Samsung logo while it's booting up, then I recommend arranging for the device to be inspected by one of our engineers at an authorised repair location. With this in mind, please head to samsung.com > Scroll to the bottom of the page > Contact us, and get in touch via your preferred channel, and an advisor will be able to make the necessary arrangements for you.
In the meantime, as another troubleshooting step, please power off the the Phone, then press the Volume Up and Power buttons together until you see the Samsung logo, then release the buttons. This should take you to a Recovery menu, where you can use the Volume Down button to scroll to Wipe Cache Partition, and the Power button to select it. Use these buttons to navigate any remaining, on screen notifications, and let me know if this helps.