Overnight my Galaxy S7 was installing a system update but it gets to 31% and turns off then reboots itself and then repeats the process.
I have tried the following but no change:
As soon as it reboots the process starts again.
Try hooking up to Smartswitch to see if this helps.
If not then try a hard reset although this may wipe your stored personal information.
A Samsung Experience Store or Samsung Service Centre can take a look.
Current Phone ~Samsung Note 20 Ultra 5G SM-N9860_256Gb SnapDragon 865+ Samsung One Ui 3.1/ Android 11.