After changing abs actuator 12v accumulator is becoming dead in few hours.

did you charge the 12volt battery after doing the work? Does the 12volt still drain quickly after recharging it?
have you had the 12 volt load tested? and how old is the 12 volt battery?

 

The C1241 is no surprise; it reports a low supply voltage arriving at the brake ECU. That does not always mean the 12 volt battery is dead, but in cases where you already know the 12 volt battery is dead, well, that's what it means.

Figuring out why the 12 volt battery is dead, that's more puzzling.

Your description is also a little puzzling, because you have just worked on the brakes, and the brakes include a part called the "accumulator" (for fluid under high pressure), but after that you seem to be talking more about the 12 volt battery (which can also be called "accumulator" in some English dialects), so that when you say "the accumulator becomes almost dead" there's a bit of uncertainty what you mean.

Are you saying there that the 12 volt battery is dead (as you seem to be, and consistently with the C1241)? Or are you really talking about the brake accumulator in that part of your description, and if so, can you say more about what you mean in calling the brake accumulator "dead"?

 

Did you watch Pro, John Kelly' video in the other thread you posted to, asking if there was a fix found?