Hi everyone, I have a problem I that I cannot figure out with my 2007 Mazda 3. I have been working from home so I am not driving my car daily like I would if I were working from the office, its a commute to work car, I have truck that I drive at other times so this car sits parked a good bit of the time now. Two weeks ago I drove it for a while and apparently I turned on an interior light and did not turn it off. I went out of town for a week and when I returned I went to start the car and the battery was dead..completely drained. A multimeter registered 0 volts across the terminals. I attempted to jump it with another vehicle but it was too dead so I hooked a battery charger to it and left it overnight. The next day the battery was fully charged and passed a load test, but the car will not start, turn the key the instrument lights works, windows go up and down, radio works, lights and turn signals work. Everything works normally but the car wont crank, turn the key and nothing, no click no nothing as if trying to start it without the clutch pushed in. The security light flashes rapidly for a couple of minutes then the series of flashes is one flash...pause ....then 6 flashes so this tells me its DTC 16. Also there is no communication between the obd port and the ECM. I checked all fuses, check power to coils from fuse 69 per the wiring schematic, all good, checked power to start relay, good, but the switched ground from the ECM is not going to the start relay so apparently the immobilizer system has commanded the ECM to suspend the ignition and start functions. I introduced a ground to the start relay and the key will turn the engine over but no start since the ignition circuits are disabled. I jumped the clutch switch and still no luck, I have tried both keys with no luck. Remote fob locks and unlocks doors and lights flash with the lock and unlock command. The only thing I can think of is the battery was dead for so long the immobilizer system has lost the memory of the chip in the keys and its thinking an improper key is attempting to start the car. Any advice would be a great help before I resort to towing it to the dealer that is 60 miles away to have the keys reprogrammed and the computer reflashed...HELP!