iPhone X went black screen.

After charging overnight, I woke up and cleared my notifications and started my daily Twitter scroll and in the middle, my phone just went black. Basically died. No sounds no nothing. I tried all the TS steps quick up vol, quick down vol And hold right button until Apple logo shows (hard reset). Same steps while connected to my MBP and nada...it doesn’t even see the phone connected (also tried all steps after charging for an hour) Since I traded my 6 plus I’m left with a 5 as a backup... Question is if I saved files to my files app under “on this iPhone” are they gone if I only do iCloud backups? They are sending a replacement phone... $1000+ iPhone lasting 2.5 years is concerning... I baby my tech just in case you were wondering.