Hi !
I had an ACA500plus, wich I tried to update... so I unpacked the 0.146 menu (from there: http://wiki.icomp.de/wiki/ACA500plus_Firmware) to the root of a CF card.
I launched the Flash Update process (F8 and F), then everything went black with a strange "low" noise (like a slow spinning fan), and a burnt smell.
Now, if I plug the ACA500plus, my Amiga won't boot: no leds, nothing... still this strange noise, but nothing else !
If I unplug the ACA500plus, then my Amiga starts...
So I assume flashing the ACA simply destroyed it !!!
Great...