Did you check phasing of the 4 bricks ? Anytime you have more than one power transformer phasing the transformers is critical to preventing damage!!! When phasing is wrong, the 18V outputs of the brick adds up to 36V or more and will blow something sky high. Again being this happens when certain outputs are connected sorta points to a possible phase issue.
Link to a post that contains a memo from Lionel about certain known out of phase 180 watt bricks https://ogrforum.com/...90#48171004082107890
This is partially the reason why the ZW-L was created and the ZW-C was discontinued. The ZW-L has one internal transformer and it's all but impossible for the 4 outputs to be out of phase. Because the ZW-C uses external power inputs from bricks, then those individual bricks could be out of phase.
Another known issue of the ZW-C is being incompatible firmware with Legacy so there was an upgrade chip but the are no longer available. Anther known thing is the plastic brackets holding the throttle potentiometers to break.
Example topic that has both of those problems (broken pot brackets and Legacy capable firmware chip upgrade) https://ogrforum.com/...zw-c-with-180-bricks
Just checked on the upgrade processor chip link and it is still out of stock https://www.lionelsupport.com/...-PROGRAMMED-S01-CODE
ZW-C video that is a little dated https://www.youtube.com/watch?v=g5A-KFr5SS4
