Ok, might seem like a silly question, but are you sure you've replaced the right 30A? I know on my trailer, there's a 30A near the battery that runs to the tongue jack. Supposedly, there's a separate 30A (or maybe a breaker) that runs back to the converter/distro in the trailer. I'm not sure where it is yet as I haven't had to look for it. I've only ever replaced the tongue jack one.
If yes, then it's time to get out a test probe and start checking for where you lose power. It's most likely going to be somewhere along that line between battery and your distro panel. Or possibly in the panel itself.
There's no use crying over spilled milk, unless it's on your keyboard.