We have found this issue to only affect the sp15 model of laptop. The symptom is a battery that will not charge, when in windows it shows a 0% charge and it will not exceed that amount. The following steps have been proven to fix the issue, if your battery still does not work after then it is a bad battery.
1) Reflash the BIOS then the EC
2) Laptop should shutoff after EC update, remove battery and power.
3) Let sit for 5 minutes and put battery back in and plug power back in.
4) Let charge overnight, should be good to go in the morning.
You can find the Bios and EC at the link below.