Sounds like a possible power overload.
What type of lnb are you trying to power with your 800 ??
A triple lnb is a power hog and if you have a long run to the dish, you could suffer a voltage drop.Could also suffer the same problem if you have a bad run to the dish,bad connections or a poor ground.
Disconnect all cables from the box and restart the box.
Does it stay on with nothing plugged in ?? If it does, you know the problem is in a cable or connection.If not...its something with the box.

Post your results.

good luck,
AFtester

__________________
Testing:
CW-800
CS-6000
SV360P
SV360E
Soon ...K-box
Dish pro plus
Dish 1000.2
33" fta dish,linear lnb and motor