screen is black-wont turn on. i need to backup before sending in for repair or replace. How?

this happened to me three times with my XS max plus's. one time some how, the back up got "turned off". did you log into www.icloud.com, and see if there is anything there before you worry? your pictures and messages are backed up separately from the cloud which good. as long as you know your app pass words, your straight, or you can reset them when you restore your iPhone or they send you a new one. the only way you'll be in trouble is if you never backed up ever. one time I walked into the apple store and the phone magically unfroze and just worked again, the last time, well no joke, the phone is a paper weight still sitting infront of me, as a sort of science project now. but, I am still researching the cause, and malicious takeover is what I'm aiming at. log into the appleid.apple.com and down load a copy of your data. its under data and privacy, and then click where it says manage your data. down load everything, usually select the smaller file sizes, so you can save and down load faster. it will be ready in a few days. make sure you do this! it has EVERYTHING! there. do this before you mail it in. seriously!! this will be your saving grace, every text, transaction, app, purchase, comment, ip, wifi address, email.... everything!!!!! it will even show you what the last time down to the second is, that it was actually working properly, before it froze, and the ip and if any account take over or malware or attack, what ever, caused it.

You don't.

Backups should be made before the phone fails.

If the screen is completely black then it could be quite a serious issue. If you can start the iPhone at all, you would have to unlock the phone to take a backup because the data is encrypted