Re: no start 2000 WJ 4.7
They key symbol light on the instrument cluster activated, indicates that the SKIM (Sentry Key Imobilizer Module) detected some fault. Try the spare key first to see if that will solve the problem. I heard some stories before that the SKIM could loose the key information and that only reprogramming would help. But as long as the SKIM is not accepting the key as valid, the light stays on and the engine won't start.
JEEP Grand Cherokee 4.7 Lmtd 2004
HID 8000K in low and fog / Quad Squad member
Monroe Reflex shocks /
Pirelli Scorpion ATR 245/65/17/
Transgo reprogramming shiftkit.