Looks like @Unnamed posted up the customer service contacts
One thing that does make soundcore better than most others is the support (official channels).
When contacting them, let them know all the steps you tried, and they’ll work with you to get things working.
I’m thinking there was also another rave thread relating to partycast, and I’ll see if I can locate it.
Did you try both the double click and the long press on the second rave mini after removing the one from the Bluetooth list?
Note the app will only connect to one device at a time, so similar to the attempt to setup partycast, you’ll need to do one at a time.
Remove all of them from your phone Bluetooth
Turn both minis off
Turn off Bluetooth on phone
Turn back on one mini
Turn back on BT on the phone to connect to the first one
Don’t turn on the second mini…
Should be able to get through to the options by the 3 dots in the top right corner (if memory serves) to get to the firmware update.
If this works, it will take a bit of time to update.
When complete it will make the startup sound, and you can then turn off the first and repeat the process with the second.
Hope it works for you, and I’d suggest that in parallel you get in with customer service.
There is a big product launch today. So if you put in a request today, I’d say you should hear back by Friday.