Factory reset iPhone XS Max?

Hello everyone,

I am currently using an iPhone XS Max. The battery died while I was sleeping and when I charged it again, the screen became all glitchy with multicolored stripes. I cannot access my phone at all and, cherry on the cake, iTunes will not recognize the phone (I already tried to reinstall iTunes, I tried plugging the iPhone with two different USB cables and to different USB port, also my iTunes is updated)! Now I am willing to return the phone back to the seller so they can send me another one but I also need to delete all data from the phone, except I cannot for obvious reasons. I deleted the phone via iCloud but I do not know it it is safe enough.

Any solutions for me?

Thank you very much,

July.