REVscene Automotive Forum - Cranks but won't start

I've had my 2004 Toyota Matrix for 5 years and there have been at least two owners before me. A few nights ago tje interior light was left on overnight and drained the battery. Next day though it was odd that several attempts at jump-starting the car would cause the engine to crank but not start and no interior lights would work. We then removed the car battery and charged it fully with a battery charger overnight, and when we reconnected it the same thing happened: car would turnover but not start, and no other sign of power (no lights will work, etc) except the red SRS warning light which goes on after about seconds like normal. Just bought some gas yesterday and added another Jerry can to be sure. The fact that it cranks and cranked when boosted would suggest that power is not the issue, but then again there is no accessory power even now with this charged battery.

Trying to research this, I'm wondering if there is something with an immobilizer system going on. Calling a dealership, apparently our VIN is not a model that was sold with a system. But perhaps a previous owner installed a system that we don't know about. There is a red LED just under the CD player display that I think flashes periodically when the car is off. Our keys don't seem to be chip keys; we each have a remote that opens doors, and a key with a black plastic head that does not say Toyota. I think we've made copies of that key that open doors just fine, and I think started it too. We've tried unlocking and locking the doors with the key because people have said this is a way to reset immobilizers, but still the problem.

If there is an immobilizer system going on that I never knew about, can I do anything?? I was hoping to solve this myself, hire a mobile mechanic if I have to; towing to a repair shop would really hurt the wallet, and towing to a Toyota dealership is more than I want to think about. Thanks for any help!