To reset a non responsive MTH decoder follow these simple steps.
1. Place the locomotive on the Mainline track
2. Select address 55
3. Enter OPS mode programming
4. Select CV55 and a value of 55
5. Write to the decoder
This will reset the decoder to address 03. Once reset, the decoder can be programmed. MTH decoders are best programmed in OPS mode programming on the Mainline.
NOTE: When programming in OPS mode, remember to select the address of the locomotive you want to program or you risk programming all the locomotives on the layout.