For three weeks occasionally when shutting off my 2013 Model S Performance the “Car May not restart” would pop up. Then after upgrading to the latest software version the I got two errors, “ Car May not restart” and BMS w026. In addition upper power limit was lowered and regenerative brakes were disabled. I took it to the Rochester service center (overwhelmed took 4 weeks to get the car in, hey Tesla build another Service Center in Upstate). The technician’s suspected moisture in the battery pack. When the pack was pulled all seals were intact and good condition. The main fuse was dry and good. When tested the battery had no faults. The technicians reinstalled the pack and all errors disappeared. They tested driving and charging with no problems. The diagnosis? Possible moisture or dirty connection that was fixed when they cleaned off the connections. Total cost - $199.