[tofupwr]

Hope someone can help. The 335xi is not starting at all and no light is on. It wasnt the first time. But previously the car started after awhile. This time it is not starting even after a day. My research is it might be the battery or the ibs. Checked voltage on battery, it is 12.7v. I think that is normal. Checked the ibs against ground, one is showing 5v and the other one is showing zero when they are disconnected. When it is connected, the one was showing 5v become zero and the zero become 5v (reversed). Is this normal or not? Cant think of any other reasons.