I have a RHB 430N unit on a 2016 Jeep Patriot. I think it has the screen/radio from the '15.
The process to update this to begin with is long, convoluted and filled with pitfalls. If the power turns off, you're screwed. If anything gets pulled out too early or disconnected, you're screwed. If the odds of fate are slightly at a disadvantage that day, you're screwed. The system has virtually no ability to recover from a mistake, and is pretty crappy at letting you know what to expect when you have to wait 10+ min for something to happen as it loads the files. That said, I was able to successfully go from "bricked" on my nav, where it would just say "Guidance by Garmin" continuously in a twitchy way, to a fully working and updated system.
Absolutely DO NOT pay a dealer $1k + to replace this unit just because they aren't technically knowledgeable enough and/or are too lazy to fix the software on this. In the vast majority of cases this problem is going to 100% be software related.
IF YOU GET THE BRICKED LOOP OF DEATH ON THE NAV:
Don't panic, something got botched in the update or the software is corrupted in some way. Luckily the radio is basically a tiny, terrible, fragile computer and when tiny, terrible, fragile computer's have software that is corrupted you can just re-install it.
The way to get out of this infinite loop of death is to do the following:
1. On your computer go here:
Gracenote Update for MyGig RHB | MyGig RHB 50.01.01 or 33.01.23 Software Update. Download the 50.01.01 zip. Replace the file /Garmin/gupdate.gcd on your "City Navigator Update" SD card (or possibly just add this folder/file to a blank USB) with the gupdate.gcd file in the download (after unzipping). This will get you a copy of the 6.10 nav software. For some reason, in my case it only worked to revert back, do the second update, then update maps.
2. Go to your car, turn it so that you have power, and make sure your radio is off with just the clock showing. Then hold down the buttons MEDIA + RADIO + MENU. After a few seconds the engineering menu will appear. This is the backdoor application which will let you make an emergency install of the navigation software without being able to access the navigation software to do so (kind of a dumb system honestly lol)
3. In the engineering menu find "PND" > "Emergency Update". Put your USB/ SD card adapter in the USB on the radio and wait 5 seconds. Then tap "Emergency Update". Confirm everything and it should load the update from your drive and start downgrading (or upgrading) to 6.10 nav software. FYI - I had my actual radio upgraded to 52 - not sure if that makes a difference.
4. IMPORTANT - Once the update is done, and it tells you PND is done, take your flash drive out. Then in the menu go to END. Now it will either restart or you have to go to the nav tab, but you should get the message "Guidance by Garmin", but just wait and you should get the version number and copyright show up. If you get that, it's working. It may say "Software Loading" or just hold on one of those screens for a LONG time. If it does, just keep the power on and let it go as long as it needs, eventually you will get to the other side and will have a working 6.10 on there. From there you can do a second update if needed etc and can continue the update process for your maps, nav etc but that will get you out of the death loop.