This happened to me a few times when I first started out.
I kept notes in case it recurs in the future:
1. remove usb connector
2. open back cover and hold the 'OFF' pinhole for 10s until you get 3 vibration - this turns off the phone
3. press volume down, then insert usb charger (which is plugged to your pc) - this puts you into flash mode
3. open flashtool in pc and choose flashmode, and 266 kernel (or other kernel of your choice) to reflash. And follow the instruction to re-flash the working kernel
On item 1, google for where the 'OFF' hole is.
On item 3, you might want to fire up SUS or PC Companion rather than flashtool (I did not try this so don't know if it will work)