I have athearn genesis f-7a it will not go forward at all it will go in rev that in dcc in dc it dose not move at all help the cv sound works
If this is a factory equipped decoder, it's an MRC. MRC decoders are known to have a very high failure rate. You probably have a defective decoder and need to take the locomotive back to the place of purchase and exchange it.
Try a full factory reset.
First make sure that only this one engine is on the powered rails. If not, you'll be sorry with what happens. Only the one engine on the programming track or the layout.
Dial in Address 00, set your programming mode to Ops mode (programming on the main), and do the factory reset per that decoder's instructions. It may be as simple as CV8 programmed to a value of 8, but you must determine that for yourself.
Then try the engine on address 03. If it seems fine, you should be fine and can try to change the address back to whatever you desire. If it accepts the reset, but does the same thing, you have a defective decoder.