The Acer Aspire One has its own built-in BIOS recovery routine, allowing it possible to flash the BIOS even when the system doesn't boot anymore. It's feature meant only for emergencies it may void your warranty, so use at your own risk.

Execute every step carefully!

Step 1 :

Format an USB stick with FAT file system.
 

Step 2 :
Download the latest Aspire one BIOS, then put both Bios and the FLASHIT.EXE software file in the root directory of the USB stick.

Step 3 :

Important, rename the BIOS file to ZG5IA32.FD and do not remove the USB stick.

Step 4 :
Turn off the A1 and make sure both battery and AC adapter are connected.

Press the Fn+Esc key, keep it pressed and push the power button to turn the Aspire 1 on.

Release the Fn+Esc key you will see after a few seconds, the power button blinking.

Push the power button once at this time the acer One will now initiate the BIOS flash, do not interrupt it under any circumstances.

Wait until the power button stop blinking, the AA1 will reboot shortly after. Wait patiently.

Now the BIOS has been flashed so all settings reset to default.

If for any reason you made a mistake during the procedure let it unable to reboot by itself wait 5 minutes before turning it off( just to be safe that it isn't still flashing the BIOS).

Bonus :

I would really recommend u to disconnect !!all!! USB devices, especially storage class, from your netbook before doing a reboot.