I just got an iPhone 13 and I’m having screen glitches. Lines appear randomly, and sometimes touch input doesn’t work. I updated the software and restarted it, but no luck. Any advice on what to do next?
Having screen glitches on a brand new iPhone 13 can be super frustrating 
. Lines appearing randomly and unresponsive touch input sounds like a hardware issue, especially if you’ve already updated the software and restarted. It could be a manufacturing defect.
First thing I’d suggest is performing a hard reset. On iPhone 13, you can do this by quickly pressing and releasing the Volume Up button, then the Volume Down button, and finally holding the Side button until you see the Apple logo.
If that doesn’t work, boot up your phone in Safe Mode to see if a third-party app is causing the problem. Sometimes apps have conflicts that mess with the touch screen.
But honestly, if the glitches persist, your best bet might be to contact Apple Support or visit an Apple Store. Since it’s a brand-new device, it should still be under warranty. They can either fix the issue or replace the phone for you. Glitches like these are unnaceptable for a new device, and Apple usually takes care of such problems pretty efficiently.
Keep us posted on how it goes! Good luck! 
Honestly, if you’re seeing random lines and touch issues on your new iPhone 13, I’d be pretty ticked off too. 
It’s great that you’ve already updated the software and restarted, but like @shizuka mentioned, it does sound like a hardware issue. Hard reset and Safe Mode are good steps, but if those didn’t cut it, I’d suggest looking into a couple more things.
Check if the problem happens when your device is cooler vs. warmer. Sometimes, a device overheating can cause weird display issues. Maybe try using the phone after it’s been off for a bit in a cooler environment.
Also, inspect your screen thoroughly for any visible physical damage, no matter how minor. Sometimes even a tiny crack can cause these issues.
If you’re brave, you could also try restoring the iPhone via iTunes/Finder to factory settings, but make sure to backup all your data first. This will rule out any software issues that could be persisting even after you did a simple update.
If all else fails, take advantage of that warranty ASAP and let Apple take the mess off your hands. It sucks diving into repairs with a brand new phone, but it’s their job to make it right! 
Let us know what you end up doing, and hopefully, this gets sorted out soon for you!