Machines with WAN card might cause battery drain - ThinkPad T400, T500, W500
If left for an extended period of time, the thinkpad battery will completely drain even if machine is in suspend or hibernate or power off state. The cause is the WAN LED on the LCD bezel is still lit.
The WWAN card gets into an unusual power state and the WAN LED remains lit. This lit LED will deplete the battery charge. This unusual power state is NOT a reason to replace Hardware components. This situation is rare but has been reported.
Any of the following ThinkPad systems configured with WWAN mini-pci card running on Windows based Operating System maybe affected by this symptom:
Update machine to latest bios available from Lenovo.
Upon completion, load bios defaults. Perform the following steps to load bios defaults: