S7 Edge possible hardware issue
Hardware failure will indeed cause a phone from completing the boot sequence without a doubt. If you own the device outright, I would suggest flashing a custom ROM such as AEX. Runs flawlessly for me. 


Download ODIN flash tool on your PC. 
Go to the site Download Centre|Aosp Extended, find your device and download. 
Find  a TWRP image.tar for your device.
Download Magisk 17.1 from the XDA site. 
Plug phone into PC and open ODIN. If ODIN finds your device, you'll see "COM3" (or whatever) at the top right. 
Put a check mark in the "AP" option. 
Put the TWRP.img.tar in there. 
Click start. 
Boot back to recovery and click wipe and swipe. 
Move the ROM you downloaded from PC to SD card. 
Reboot to recovery.
Click install.
Find the ROM, click and swipe. 
Boot to system. If it boots (takes about 3-5 mins) you're good. 
Optional: boot back to recovery and install Magisk. 


Now you have a great ROM and is rooted. Once you're happy with the device, boot back to recovery and make "Backup". By the way, you will not and cannot backup and restore unless you get a perfect image and all partitions into some sort of 0755 folder with a blocker file in front on your PC. Then, you need to decompile, and recompile into a flashable zip. Not very applicable.