That is rather odd for it to say that.
Try restarting the device in "Safe Mode" and see if you can get in. If you can, while you will have limited access, you will also know you need to check the device for bad apps, viruses, malware, etc.
To get into "Safe Mode" please do the following.
1. First turn off the phone.
2. Next press and hold "Power" until you see the manufacturers logo on the screen, then release the power button.
3. "Quickly" press "Volume Down" and hold it for few seconds until you see the message "Safe mode: ON" or something similar.
4. If you wanted disable it, simply repeat the steps above, and you should see "Safe Mode: OFF" rather than on.