Windows 10 - flickering screen? Can't do anything?? - help!

I am not a primarily a Windows user, so thought i'd ask here with this problem.
Just borrowing a good spec gaming PC to see if I can use for audio running Windows 10.
It was all formatted, and after a few turn ons, it seemed to do its own thing with Windows updates that it needed?
Anyway now when i launch, even before getting to the password page to get into the machine, the PC just has a continuous flickering screen every second, and i cannot do anything??!!
just random intermittent flashes that wont allow you to do anything or get anywhere?
all i can do is shut down???
Any ideas what this means and how i move on or get around it??
Very frustrating!
Just borrowing a good spec gaming PC to see if I can use for audio running Windows 10.
It was all formatted, and after a few turn ons, it seemed to do its own thing with Windows updates that it needed?
Anyway now when i launch, even before getting to the password page to get into the machine, the PC just has a continuous flickering screen every second, and i cannot do anything??!!
just random intermittent flashes that wont allow you to do anything or get anywhere?
all i can do is shut down???
Any ideas what this means and how i move on or get around it??
Very frustrating!