Recently my 2013 energi has a problem, the HVB cooling fan in the trunk stays running until the 12v battery is dead.
The only way to stop it is pull the fuse in the underhood box.
The car is cold, not been driven, not plugged in.
Some times the fan changes speeds form low to high.
If I open the trunk it will stop for a few seconds then start running again.
I pulled the 12v battery cable to reset and the issue went away for about a week but then returned.
car has 65k miles and have not had a single problem with it, other than a couple recalls [airbag, seatbelt tensioner,]