"G" gauge is a two rail system, DCS was first designed for "O" Gauge three rail. It makes a difference which way the locomotive faces with two rail. The negitive rail shuld be on the right, under the engineer's side of the cab.
If you place the locomotive on the track in the wrong direction, it will usually will start up and accelerate to full speed. If you put the locomotive on the track in the right direction it should stay there until you make your move with the Remote. Your first move should be the "READ" button.
I have found that if the locomotive starts up, moves and shuts down, the TIU can not find that locomotive. Weak Track Signal from the DCS to the Locomotive, NOT WEAK VOLTAGE.
As MTH/DCS uses the negitive rail to send the signal to the locomotive, leakage to ground will "sink" the signal without effecting the voltage.
1. Are You running lights or accessories off the track voltage.
2. If the "READ" button shows "NO DCS ENGINE ON TRACK", try on your Remote, Menu/System/Engine Setup/ Add Engine/Add DCS Engine.
3. My biggest problem was Rail Joiners, I ended up changing all 500 plus feet of track to Rail Clamps to give me at least an 8 out of 10 on Track Signal Strength.
4. Keep your track CLEAN, brass is excellent when clean. Stainless is almost as good but requires LESS Maintenance.
5. I also have the CSX Narrow Nose, remember, it has a "Polarity Switch" located, on the bottom, under the front power truck next to the fuel tank
Most "G" Gauge is 18 Volt DC, the DCS System works on 12 - 22 volts AC or DC. The Absolute Voltage Limit is 24 Volts, I do hope you have not "spiked" the micro-processor with over voltage. Please read the DCS Manual.

I have 10 MTH "G" gauge locomotives plus 5 Aristo-Craft Locomotives upgraded to DCS. Love the System.