2007 BMW E91 no-crank and a broken battery positive lead
Jake_Petersen_E91 reported a no-crank condition on his 2007 E91 N52. Replacing the starter, ground strap, and a relay behind the glovebox did not change the symptom. After removing the battery, he found the main positive lead broken inside the battery box. A few days after a replacement lead arrived, he reported that the car started.
The reported symptom and initial attempts
Jake_Petersen_E91 said his 2007 E91 N52 had lights on the dashboard and one click from the engine bay, but the engine did not crank. He reported replacing the starter, the ground strap under the driver’s side, and a relay behind the glovebox; the behavior did not change. A reply by gbalthrop identified the removable relay on the junction-box fuse panel as the KL30g accessory relay.
A broken lead inside the battery box
While removing the battery, the owner found the main positive wire snapped inside the battery box. He said he was ordering a replacement lead and would update the thread.
The owner reported that the car started
A few days later, after waiting for a new positive terminal lead, the owner reported that the car had started again. The thread does not document the replacement procedure or establish that this single case represents a common failure.