My chilis in garage are not working if cold. Yesterday they stopped at 3 am and today same. I rebooted everything and LEDs are blinking well, but my raspberry pi doesn't recognize the devices. They may be gonna recovered Morning as the yesterday case. How are your chilis? Are they okay in -7 Celsius degree?
I found the reason. U25 temperature sensor doesn't work properly under low temperature. I covered it with a small tape and now all chilis are okay.
Out of curiosity, how did you verify that the temperature sensor wasn't working correctly? It is specced to work linearly down to -40C, but I haven't actually tested that.