S7 Edge possible hardware issue I have this Samsung S7 Edge. Phone worked fine. Then I placed it in box. After 4 months I decided to use it again. Of course battery was empty. I charged it a bit, and it would not go past the Samsung logo screen.

I have tried all things that I found on internet, like resetting it, and clearing cache but it did not fix the problem.

I took it to service, and after couple of days I got reply that the flashing did not fix the issue. Service man said that one of the chip is bad, and that is the reason it does not boot up. Also he said it is known problem with S7 phones. Fixing it is more expensive then to get another S7.

I do know hardware failure can prevent the boot, and many other things. I am wondering at the statement 'It is known problem to S7 phones'. If he is not telling the truth, I would rather try with another repair shop, before throwing the phone away.
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.