Mac Pro 5,1 wont accept startup keyboard commands or installer after 'MacOS could not be installed'

Hi

I have a Mac Pro that was updated to High Sierra (yes I know its old, but it has expensive software that wont go higher), did a firmware upgrade, and I let it run, and next day I found it saying 'MacOS could not be installedon your computer - error while loading installer'. have tried booting in safe mode, pram reset, or select boot disk - it seems no matter what I press during bootup, has no effect. I tried two keyboard, one wireless I used before, and a classic wired apple keyboard. Both are functional after the recovery loads.

So I did reset the NVRAM from terminal, and I decided to do a clean install, and I have created a High Sierra install USB. Since I cannot select a startup disk at the startup time, I have to run startup utility from recovery. However, it wont see the HS installer... I then tried anold Sierra installer, no luck. Finally, I was able to have a USB drive with a Live OSX recognized, and it started the computer. It seems the system SSD is bust...there is no recognizable partition there.

But how do I do a clean install if I cannot get any installer started? I am at loss.