I have a Bachmann Spectrum locomotive bought new. It ran a while ago but I'm afraid I may have inadvertently changed something. It runs on DC but is completely dead on DCC. I am using an NCE Power Cab and trying to reset all to the factory settings. Chat GPT says it should be as  simple as resetting CV8 to 8 and it'll be back to factory settings. This doesn't seem to help. Any ideas? This locomotive has sound. Not sure the decoder. The ISO drawing says it is P/N  H4915-X0001.