Help connecting Devo7E and RX701

Sounds like your receiver is not getting any power (or its broken) since you are not getting any LED on it.

Could you try to first connect an ESC directly to your receiver on the throttle channel (just remove your props) and see if you can get it working that way. Reason being is the other possible issue is that the PPM encoder is not outputting power to your receiver. You might need to solder the jumper on the back of it to enable that