Hi all,
Thanks to various posts here, I was able to 'repair' my Carplay2Air module.
I received the device last Wednesday (delivery in 5 days, so pretty fast). Connected my car (Hyundai Kona EV, 2019 model) to my iPhone SE and in worked fine immediately - but if you start using it, might be good to make sure your car 'forgets' your phone and your phone 'forgets' your car. I didn't do this, so you get lots of connection requests that are confusing.
Anyway, I immediately upgraded to the latest firmware by browsing on my phone to
http://192.168.50.2 - upgrade was successful, but from then on the device wouldn't connect properly. Yes, it connected fine to my phone, I also could access 192.168.50.2, but the screen in my car was hanging at 'connecting...'. Make the device forget my phone and my phone forget the device and starting from scratch didn't make a difference. Plugging out/in of the Carplay2Air didn't make a difference. Power cycling the phone didn't make a difference.
This morning, I did:
- format a 16GB USB stick to FAT32
- browsed to http://112.74.112.110/download/2020-01-20 (one-but-last at this moment) and downloaded the two '.img' files to the USB stick
- Plugged the USB stick into the Carplay2Air module's USB port
- Plugged the USB connected of the Carplay2Air module in a regular USB charger (not a laptop or car connection, just a charger)
- Waited for a few minutes - did the laundry while waiting, not sure if that makes a difference in the result

- Plugged the Carplay2Air in the USB port of my car - and it immediately worked fine again. Only the steering wheel button for Siri commands misbehaved a bit - I got the Siri sound effect, but it didn't respond to my commands.
- On my phone I browsed to http://192.168.50.2 and decided to upgrade to the latest firmware - even though that one gave me the problem initially.
- ... but after a minute or so, the Carplay2Air device rebooted and connected fine again. And even the Siri steering wheel button behaved normally again.

I still need to test a bit more to see if the device works reliably, but above manual could help others stuck in a similar situation.