Don't worry. Each Zing comes with a "bootloader" firmware that will restart the device even if the main firmware becomes corrupt. Here's how to recover your Zing.

1. Unplug from outlet, let the internal battery drain completely -- usually takes between 24 hours.

2. Plug the Zing back in

3. A card named "Unknown Zing" will popup in the iOS app, click on it to resume and complete the update process.