Focusrite 2i4 issues

I recently bought the Focusrite 2i4 and it has been working grand until recently. I was playing guitar through it when I stopped for a moment to do something, then I came back and it stopped working. When I unplugged the interface and plugged it back in, the gain nobs blinked red at me. The interface won't work and it does the blinking every time I try plugging it in. Is it because I didn't use a DI box? What is the reason? How do I fix it?