Just had that happen to me.
2018 SV with 8k miles, built in March, bought in June
Got "Service EV system unable to restart" message. So I did the usual checks of 12V battery and all that but got nowhere.
Leaf Spy pulled two DTCs:
P31E7 000B Restart inhibition EVC-310
P0AA6 1A08 Hybrid battery sys isolation fault EVC-157
Had it towed in, dealer just called to tell me it's a bad cell in the pack and it'll be at least a week of fixing.
Driving gas loaner meanwhile