Power converter

Turn off ALL breakers in the RV panel and try again. Post the results.
If no trip turn the breakers on one at a time starting with the main.
If it trips with all breakers off you have a short in the cord or a short at the connection at one end or both.

You should say "power centre" instead of "converter" so we don't get confused. The converter is in the power centre and just converts 120v to 12v.

Meanwhile you do have a ground fault somewhere in the rig, which is why he cut off the ground prong (it is not "broken" --he cut it off) instead of finding the problem and fixing it.

Meanwhile, don't stand in a puddle and put your hand on the skin of the rig. :(

Agree, if you are not familiar with electrical issues, get a pro to fix it. In a 1996 rig it could be anything, but the first suspect might be the shore power cord plug itself that he cut the prong off. Perhaps a new plug on that cord, that is properly connected to the three wires would fix it right there. You have to replace that plug anyway with a proper three-prong.

If not, it is a time-consuming task to find the ground fault in the rig, and time is money (100/hr?) so lots of motivation to try to find the problem yourself.

That gets you to the suggestion earlier to try one breaker at a time to narrow down which circuit is guilty. Then you can chase down what on that circuit is guilty. (But start outside with the shore power cord plug in case that was it and save a bunch of work checking inside the rig)

the power converter supplies 13+v to charge the house batteries and power 12v items, are your batteries charging, did everything work on the camping trip, what about the fridge, did you use propane or put it on automatic and use electric

you have a short to ground in the wiring
this could be one of several things
frayed wiring in the 30amp shore plug
a shorted 120v heating element in the fridge
a screw thru some wiring somewhere

for testing you need to turn off ALL the circuit breakers in the breaker box of the rv
plug into shore power
did shore breaker trip ? yes/no . if yes, take your cord apart check both the male plug and the connections at the RV
if NO proceed
turn on main breaker in RV panel, only the main
shore trip yes/no
if no
turn on..only one breaker at a time
you are looking for the circuit with the problem ?

First NEVER ever plug into a pedistal with the breakers on.
Find your electeical panel and turn everything off, including the converter. Plug in, start turning things on one at a time until the breaker trips. There is your problem. It is quite likely that your drawing too much power because the WH and refer are trying to start up.

The mods must be taking a break from moving these posts.

You have an electrical problem somewhere.
Strongly suggest a qualified electrical person to help you.