Call Uconnect and tell them
Here's the thing: the update bricks the head unit /computer if the head unit (uconnect computer, really) has had it's cellular modem/wireless card malfunction. This is an old issue common on a lot of uconnect units-the update does not work because the cellular modem/wireless card is dead, the update times out, and the uconnect system is bricked.
The fun part of this is, the TSB related to the issue outlines all of this: it tells the dealer to go into the Uconnect menus, look for the cell modem/wireless card ID numbers, and if the numbers are not present, the uconnect system cannot be "updated." The system must be replaced. My van's ID numbers are missing, so my head unit is not able to be updated.
You can look in your head unit/uconnect system after placing the system into 'dealer mode" and see if the ID numbers are present or not, which will tell you if your radio/uconnect system can be updated or not.
Chrysler can do a "goodwill" repair on these radios within some limits.
What year is your van? How many miles?
My system/Pacifica is facing the same issue, but I just bought it certified as being flawless and with a working navigation system, so the non-chrysler dealer I bought it from is having it fixed on Monday. Before I bought my van, I looked into known weak points of these things and was ready to rumble.
As a result, I can actually teach you how to fix the overall issue with the units: you can open them up, replace the wireless card/modem with one off ebay if you can find one, and away you go. It won't help you update-the dealer will probably still try to charge you to do that-but your navigation will work afterwords.
From what I can tell, when the wireless modem/wireless card goes out on these head units/uconnect systems, the system starts displaying erratic behavior.
Have you called uconnect directly to talk to them about this? Send @ChryslerCares
a DM on here, too, and see what they say: this is a known flaw, and @ChryslerCares
has fixed this issue as an act of goodwill for forum members on here before