Sounds like you have messed up the BIOS. Me, been there done that myself.
So, you need to DL the BIOS and load in into the ACER. Here is how.
www.qrpcw.com/.../...aspire-one-bios-recovery.html

How I screwed up mine. The computer got locked up. Holding in the power
button would not turn off the computer. Had to remove the battery to get it
to power-down. Yes, no AC and no battery, she went down then. But the so did
the BIOS. Somewhere I read that powering down that way with a device plugged
into a USB port, I had a mouse plugged in, causes it. At least that is the
theory. The BIOS rev I used at that time was 3310.

Does it say "Kernel Panic"?.............

It could be anything. You need to get into text boot mode by editing grub to
remove 'quiet' or press ctrl+alt+F1 This will give you more information
because you can watch the text scroll by instead of seeing a graphical
display or nothing at all. This shoudl let you see what it is choking on. It
could even be a kernel panic.