I don't have a Solo, but I'm pretty sure that's the network light. I think it's trying to tell you you're not connected to your network. Do you know your internal ip address. Try pinging it (I suspect you won't reach it). Check you wiring and router first. Then consider the network settings. Run setup and check, if that fails try a soft reset and hard reset.
Thank you for contacting us here at the answer forum. It sounds like either the network or the power light is the one that is blinking. Here are some articles that should get you up and going.
Hope that these helps,
Sling Moderation Team