Balboa Spa Whirlpool: Control Unit not responding

I’m using a Balboa Control Unit based whirlpool/spa. Since two weeks, the control unit is completely unresponsive. There’s of course no WiFi, but also the touchpad at the pool is unresponsive and it doesn’t comsume any power.
Has anyone experienced something like that? last time it lasted for approx. 30hours (I didn’t log that) and the Unit came back on its own (I had it connected to power all the time).

It’s not THAT different from the last two years, there’s temperatures around 0°C atm, it was like -12°C for a day or two last week, but that’s nothing unusual and from my remembering, it was that cold the last two years also. The pool is now 2,5 years in use.