Softbrick: when phone is in bootloop and the only way to resolve is by flashing a rom in recovery.
The best thing to do whenever getting ready to flash a new rom is make a nanoback up!
Nano backup: Saving a rom at a working state so that in case there is an error flashing a new rom you can get back to where it once worked, and then possibly figure out what went wrong.
Bootloop: Whenever your phone just shows the manufacture logo, and reboots and then just keeps showing the manufacture logo, and no loading into rom.
A boot loop happens when you are trying to boot a rom not meant for your device.
Kernal: This is software that allows your phone software to interact with your hardware. It contains the major information that is needed for boot and your phone drivers. There is a line in the kernel that called "bootclasspath", and if this isnt what it should be for your device, you will get a hard brick as this line tells your phone how to boot.
Only way to resolve a hard brick:
1)Send into JTAG service to fix
2)Using a JTAG to fix yourself
If you have any question please dont hesitate to ask here or pm me.