After updating to Catalina I ended up with machine that only powers up a fan and disk but not even start a boot sequence, no response to PRAM reset, not even a sound while powering on, no signal to video. The installation was following according to the plan everything copied to newly installed SSD there was a reboot with apple sign, bar went till the end. Another reboot again bar went till the end an than nothing.
now only LED light is light up, fan and disk receives power and that's it – the computer is bricked. I suspect something wrong happened to EFI on motherboard while updating versions – but how can this be fixed now?? Any help not involving motherboard replacement will be much appreciated…..