Very different issue to what I was experiencing in What I'm up to today... (Upgrading M2.2.11 > M2.3.4 Dryrun).
In your case, it looks like the Web Setup Wizard has stalled. Biggest reason why I do everything in the Command Line Interface now.
When the Web Setup Wizard stalls (for whatever reason), the status will remain the same forever.
The issue why this happened to you won’t be clear/obvious, but could be down to the PHP memory_limit of your environmental settings or simply the server specifications.
Anyway, this issue has come up a few times on the forum. Reading through this post should help you get back on track: Magento update from 2.3.0 to 2.3.1 problem