UMC404HD Audio inputs 1 & 2 Distorting

[Qrez88]

Hi guys. I just bought a used UMC404HD from guitar center. I was gonna use it for streaming audio for our small church from our mixer board.
So, when I first plugged in power to the interface, I noticed that both the sig and clip leds on channel 1 and 2 were on, with nothing connected to them. Channels 3 and 4 seemed fine, they worked like normal when I connected a mic to them. But when I connected the mic to channels 1 and 2, they were distorting in my headphones from the get. Like I said, channels 3 & 4 worked fine, sig and clip lights came on as they should, and the sound was good, but 1 and 2 seems damaged I think. Sig and clip lights remain on, whether there is an input connected or not.
Anyone have any solutions to this? Or am I right in suspecting that because I bought this used from GC, it was probably toast to begin with? Thanks in advance for any help or insight you may have.

[kmitchell]

Sounds like the A/D converter for Ch1/2 is fried. I'd return it to GC and get your money back.