Thats easy:
get 3309.fd from e.g.
http://en.kioskea.net/forum/affich-95127-acer-aspire-one-zg5-won-t-boot-up
rename it to ZG5IA.FD and put it on an USB-stick.
Switch your ZG5 off, put the USB-stick into the slot at the left side.
press "FN" + "ESC", keep it pressed;
press "Power ON"
release "FN" + "ESC"
Power LED will blink for 1/2 min. wait until stop blinking.
after that: switch off ZG5, pull out USB-Stick;
Power ON: yuppi!
Gruesse aus D: Axel Paulien