Well, if you are having trouble with getting the device erased in order to set it up as new, then there are a couple of ways you can do that:
1. If you have the device signed into iCloud with Find My iPhone turned on, you can sign that iCloud ID into iCloud.com on a computer, click on Find My iPhone, and if the device is located (showing a green dot indicating it is online), you can click the device, then click the Erase button to erase it. It will ask for your iCloud passcode, but that should be all it asks for. You do not need to put in a phone number or message. Just follow the prompts until it says it is erasing the device.
Once the device is erased, then you will see the "Hello" screen. Just slide to unlock, and follow the prompts to set it up as new.
2. If you do not have the device signed into iCloud with Find My iPhone turned on, then you would need to follow these instructions from Apple on how to erase using Recovery Mode:
Erase your device with recovery mode
If you've never synced with iTunes or set up Find My iPhone in iCloud, you'll need to use recovery mode to restore your device. This will erase the device and its passcode.
- Connect your iOS device to your computer and open iTunes. If you don't have a computer, borrow one from a friend, or go to an Apple Retail Store or Apple Authorized Service Provider.
- While your device is connected, force restart it: Press and hold the Sleep/Wake and Home buttons at the same time. Don't let go when you see the Apple logo — keep holding until you see the recovery mode screen.

- When you see the option to Restore or Update, choose Restore.

iTunes will download software for your device. If it takes more than 15 minutes, your device will exit recovery mode and you'll need to repeat steps 2 and 3.
- Wait for the process to finish. Then you can set up and use your device.
Here is a link to the entire article: If you forgot the passcode for your iPhone, iPad, or iPod touch, or your device is disabled - Apple Support
Once the device is erased you would set it up the same way. Slide to unlock the Hello screen and follow the prompts.
Just so you know - for some reason, when I erase and set up my phone for testing, the Hello and subsequent set up screens are not very bright. Don't be alarmed if they seem a bit dim....(or a lot dim....)
Best of luck,
GB
