Shimano Di2 RD-RX827-SGS main unit is unresponsive

Hi everyone, I'm having issues with the Shimano Di2 RD-RX827-SGS main unit on my new bike. During the initial inspection at home on a stand and short test ride everything worked fine, I was able to pair it with the phone app as well. Until today I had a short 5km ride with my kid and I didn't face any issues either and then the bike was resting for a few weeks waiting for a nice weather (because I'm in Germany).

But during the ride today it stopped shifting, no response whatsoever. The function button doesn't respond, the LED doesn't light up either when the button is pressed or battery is removed and placed in again. Occasionally it shifted 2-3 times and then went completely unresponsive.

So far I've driven only about 10km, the battery is fully charged, before the unit went unresponsive I could see the charge in the app, also connecting to the charger it behaves as expected.

The bike is brand new and it's covered by warranty, I just wanted to check if there is anything obvious (or not so obvious) that maybe I'm missing before taking to the repair shop.