Summary: The unit I first took home had a blown channel. Exchanged it without any problem other than wasting half a day of my time. Then it worked fine for more than a year. Lately it started display F70 when I turn it on and I have to turn it on and off many times until it comes to life. Supposedly this is a blown internal fuse, though haven't verified yet. The point is, I have had two failures on two separate units in under 2 years.