My thought was, this was simply the case of the user not inspecting and replacing the battery on a PS1 or PS2 (I know this engine is PS1 from the part number and 2 dings at startup). Again, hindsight is 2020- but the board probably was NOT bad you started had you replaced the failed battery before attempting to test and power up.
The lesson to learn here is:
#1 look up the product number and get the manual and details for any MTH engine you are considering buying or have bought. It's so easy single google takes you right to the product page 99.9999% of the time. https://mthtrains.com/30-1113-1
#2 Again, downloading the manual from the "Support" tab of the product page
#3 Reading the manual and going to the battery replacement section (Page 14)
REPLACING THE PROTOSOUND BATTERY
The battery, located in the engine’s tender (see Figure 10 on page 20 for the location
of the tender mounting screws), is a rechargeable NiCad type which is continually
charged from the track when power is applied. NiCad batteries are a dry battery and
should not leak or cause any damage to your locomotive and will last up to five years or
If you notice that the sounds seem distorted or garbled at low voltages or become silent
when power from the transformer is shut off, the battery may be going bad. Before
replacing the battery, you should put the engine in NEUTRAL and leave the transformer
throttle at about 12 volts for fifteen minutes. This should temporarily recharge the battery. If
the garbled or distorted sounds are reduced, then your battery charge has worn down. You
can give your battery a full charge by leaving the engine ON in NEUTRAL for 16 to 18 hours.
(Make sure the smoke unit switch is in the OFF position to prevent harm to the smoke unit)
If you need to replace the ProtoSound™ battery, it is a special NiCad 7-cell, 8.4v battery -
NOT the 6-cell, 7.2v battery found in most convenience stores. The 6-cell NiCad is NOT
recommended for use with ProtoSound™ applications. Replacement ProtoSound™
batteries are available from MTH ProtoSound Electronics at 9693-A Gerwig Lane,
Columbia, MD 21046. A standard 9v alkaline battery can be substituted as a temporary fix,
but since alkaline batteries can’t take a charge, it will eventually wear down. Regardless, it
should give you a week to a couple of months use while you wait for your replacement
ProtoSound™ battery to arrive.
Body mounting screws of the tender in the 4 corners
Again, at the end of the day- the lesson is this was an engine made in 1997 with Protosound that contains a rechargeable battery that most likely should be inspected or replaced BEFORE attempting to power up any engine new to you that you are not aware of the state of this battery.