Emu black is not switching on after battery change

Hi everyone. Problem is that after disconnect battery. Emu black is not switching on. After switch ignition on, when fan is on voltage is around 11,65v. Is it possible that is too low to switch ecu on. All wires in adapter checked. I’m out of ideas. I would also like to ask you Is it normal that everytime i disconnect battery, it’s takim a few seconds to ecu switch on. Ignition, radiator fan is on and after few seconds it’s catching communication and fan is switching off. i had emu black in other car before and i don’t remember has it act like that.