Hey, i don't know how techie you are, but if it's not reading the ROM , simply thats a piece on the board, so either the hard drive is not connected fully, a connection isn't fully connected, or worst of all the board is “fried" (prob not)… unplug & eject everything & plug it all back in, check the little metal connector pieces, make sure nothings bent wrong, or got a hair or a fuzzy where it connects… when 8n doubt, “Google” your problem… check this page too:
[[Acer Aspire One D255E Troubleshooting]]
-good luck..