Everytime i see someone mention the battery just installed I always bring up how easy it is to get the battery installed backwards.
The thing to always do when installing a battery is always notice the battery case stamped "NEG" or "-" terminal and make sure this is the BATTERY CABLE that goes to the trailer frame ground connection which is near the battery location.
If you install the battery cable in REVERSE than you most often blow three fuses. Two will be in the Power Distribution Center and are usually off to themself and marked "REV POLARITY" or somethng like that. The other fuse will be an "IN-LINE" very close to the battery location sometimes under the trailer frame.
No HARM done except some blown fuses between the Battery connection and the Power Distribution Center connection.
It is very easy to reverse the battery connections so always keep this planted in the back of your mind everytime you touch the battery cables.
The same thing will also happen if you spark the battery cables when being installed touching the wrong terminals.
Alot of folks will use one of those cable markers you find at the autoparts stores and identify POSITIVE and NEGATIVE on the battery cable ends as another reminder which battery terminal they go to.
I have a BATTERY DISCONNECT SWITCH installed in my installation and never remove the batteries. If I need to isolate the battery for some reason when parked I Just switch the battery out of the circuit.
Dont know if this is causing your problem or not but definately needs to be looked at as possible cause.
Having a digital multimeter on hand when working around batteries is a "MUST HAVE" item for the RV Toolbox. They are very inexpensive ($7-$20) from Lowes-Walmart-AMAZON-any number of autoparts stores)
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My Digital Multimeter is a high dollar FLUKE model from my Systems Engineering working days but the inexpensive models from the local stores work just the same. Pick one up... Then you dont have to guess anymore why something isnt working DC Voltage wise. "Hmmm lets see" you are thinking... "yep I am reading 12.6VDC on the battery terminals with the Shore Power cable removed." Then measure the "BATTERY CABLES" connections at the Power Distribution Center terminals. You say "Hmmmm nothing here." Then you say to yourself "I must have a blown fuse somewhere or a bad battery terminal connection or my battery disconnect switch is open"... Now you can go look somewhere instead of just guessing what is wrong.
I wouldnt be too concerned about talking out loud unless the trailer starts answering your comments...