great thread, lots to ponder. And yes, I cheered when you finally got back in
My experience with Rover 75 alarms and flat batteries is enormous. The battery has gone flat many times on both cars.
This is what I've learned - If the battery goes flat with the car locked and alarmed on the fob, the alarm will sound when the negative lead touches the battery post....... have fob ready to unlock.
If I know the battery is going to go flat I open with the fob, but lock the drivers door with the key blade. After battery has gone flat and fob doesn't work, I recharge the battery, and this time when reconnecting it, the alarm doesn't sound.
Something else..... If the car is locked and alarmed with the fob, then I open the drivers door with the key blade, she lulls me into a sense of false security, then the alarm suddenly goes off.
Didn't know about the technique of opening the window with the key blade. Might try that for fun next time I'm out