How have you checked the cables and dish to confirm they are OK?
I had a similar problem with mine - it basically stopped powering the LNB. My set up involved 2 TV's in different rooms (STB in lounge, TV with built in Sat tuner in bedroom) being connected to the dish via a splitter. The first TV set up switched on would provide power to the LNB up till the day the s7070r decided it wouldn't. I quickly found that if I powered on the bedroom TV first the s7070r would be happily receive and display signal, change channels etc. Strange, and slightly annoying but not enough for me to buy another STB.
EDIT: If you have another STB or can borrow one, it'll worth doing a swap out to test if it's a problem with your receiver or if the problem lies elsewhere.