My S21 has randomly started turning off if I connect to charger or anything else by USB... have done everything...backed up everything wirelessly and resorted to a factory reset...lucky I have a wireless charger pad.
I should add that i have tried multiple cables genuine samsung and generics...
Just something to try, insert a usb, check to see if you can see dismount options and dismount. Also even though you have done factory reset, try finding an app relating to usb, or other apps that use the connection, eg SmartSwitch, and delete caches. If using Google and/or gmail check settings for these. Using restore may reinstall caches so go through caches, especially for the apps you were using when usb was connected.
Thanks for the suggestion, but any USB cable inserted turns the phone off and I can't turn back on unless it's disconnected. Even with no apps except the system apps you installed it turns off. I'm thinking it can only be a hardware issue now.
Based on what you've described, I recommend for you to head into your nearest authorised service centre with your proof of purchase so that we can take a closer look into this. Please be aware that due to our Privacy Policy, your device may be factory reset before being assessed. I highly recommend backing up your device via Smart Switch, OneDrive and/or Google to ensure none of your data is lost.
