I just bought a RUT240 - am considering them for a fleet of 50 rental boats. I got it yesterday, put in an ATT simcard, and had it working quickly out of the box. Today, I plugged it in to do some more testing and it will not pick up cell service. The three lights next to signal strength just flash randomly (sometimes they are all lit, sometimes just one, sometimes none) but at no point do I see signal strength lights turn on. It worked yesterday, what could have happened between now and then? Is there a way to hard reset this thing?