I am reporting the exact same issue on my ACA500 - i am running A500 Revision 5 mobo. I have a ticket open with Amiga kit but they are just telling me to clean the connectors. I have done that of course but it does not work - i get the exact same black screen as what you are experiencing. It wont boot.
Now whats interesting is i can get to the boot screen if i attach an ACA1232 but most of the time it wont boot to CF and locks up. Right now my ACA500 is rather worthless. The ACA1232 is working incidently as its been tested in my A1200.
Incidently my solder joints are horrible also - it looks like it was hand soldered and could be a refurbed unit. Here is what mine looks like.
