Hey DJ Dark,
That’s a reasonable question to ask.
Let me start by saying that I’m not aware of a single unit (and that’s counting not only Prime 4s, but SC5000s and SC5000Ms as well) that ever been put into a non-recoverable state because of a firmware update.
We have several safeguards in place, so that even if an update were to fail in the middle (via power loss or other catastrophe) the player would still be able to be put back into the update mode to flash again.
I hope that puts some of your fears to rest.