picked up a used castle everything seemed ok. i went to program it to my dx3.0 and bam i got what appears to be the red light of death . i even tried hooking it up to my castle link and it just sits there with the dim red light and the castle link doesnt think its plugged in . anybody have any input ?

I'm having the same problem. I set everything up as instructed but then I realized it was set to Low Voltage Cutoff. I followed the instructions for turning it off but now I get this red light. The only thing I can find says a red light is on when indicating full reverse. I have tried 2 different transmitters and receivers so I don't think it's the throttle trim.

Have you tried changing the transmitter throttle direction ?

+1 try reversing your throttle the red light has nothing to do with lipo. In my case the dead red light is very dim so dim you can barely even see it.