iphone X graphics card

Soon after a needed screen replacement, my iphoneX seems to have suddenly developed the dreaded 'Gray Screen of Death' scenario according to many helpful tube videos. Upon restart, the screen lights for a split second, then goes dark, remaining in pithy gray black w tiny bits of light around the outer edges, until the underlying password screen times out, triggering a power down/off.

I tried pressing screen firmly for 3 secs on top left (location of card). Nada.

Also...The phone isn't fully synced w/cloud. OS has changed from itunes & isn't as direct as before. I may have one ipad, unused & still running itunes.

Seems best to mail it into Apple for a graphics card replacement.

However, Apple (wisely) requests devices to be backed up with data wiped

before before sending in or servicing. I've run out of self help options to achieve the wipe while having the gray screen.

So I'm reaching out to our resourceful Apple community for help & ideas on...

How to enter the pw, have the phone be recognized & able to obey commands w/a cord connection from the iphoneX to my MacBook Air.

I'm very grateful to all who read this, ideas or not. Thank you.