Amiga 4000 boots and works on RTG but black screen on AGA

[Reflex]

Hello

i hava an Amiga 4000 desktop inside a microbic tower with a CyberstormPPC improved by statchu100.
IT has a ZZ9000 and two more grafic boards on the mediator (a voodoo 3 and a Radeon 9200).
Now the problem is that the computer boots up nicely with RTG modes, but i cannot get any display on AGA modes, i cannot get any Early Startup menu too.
Id i unplug mediator and all the boards the screen starts low grey then light grey, the floppy stars clicking but i don't get the purple screen that invites me to put a floppy inside.
If i boots with floppy inserted it loads workbench (i can hear the noise) but the screens stays black.

It looks like the computer works but there is some kind of problem with the chips or memory, everything worked fine until a few time ago.
Am i right?
What did happen?

[Reflex]

MoBo is recapped.
ZZ9000 has a scan doubler yes and the amiga is conncted on the SCART port of the tv too.
So i'm sure that there is no AGA output at all.

[Reflex]

Have you tried completely stripping down the A4000 to just the Mainboard only? Even taking out the Daughterboard/zorro 3 board?
Then just plugging in a RGB to SCaRT to see if you get the kickstart screen.

yes i did, same result.

I tested the MoBo with the diagrom and now i noticed that RBG test fails most of the time

[Reflex]

i bought this A4000 back in 2000 and the previous owner already removed the battery replacing it with a coin shaped one.
then it broke down during a storm and it was stored in a closet. After several years i decided to send it to repair to Hese in finland and found out that it was the SuperBuster burned by the storm, the MoBo was then recapped and worked fine.
So it cannot be a corrosion issue due to battery leaking.
Anyway ad far as i'm understanding there is some problem with the custom chips themselves or tracks

[Reflex]

only Super Buster and some GALs as i installed the 112mb hack