I've tried no HD and even the normal Win 8.1 disk but no go on that. USB key (with 8/8.1 recovery AND minimal DOS) doesn't work, nor does a Win 7 recovery DVD. Might try a CD next as it is trying to boot to optical and something fast may work (even tried the HD in an ODD caddy).
And Acer seems to have gone towards using non-volatile CMOS so one cannot reset the memory by taking out the CMOS battery (done that, out for an hour+). Have to find CMOS shorting points (none apparent) or it would seem, try to reflash the memory (but the files may not be publicly available).