[General Questions and Answers] thewildnative:
Long story short:

How do i get my current working android device to revive an identical soft-bricked device. More challenging than you think: there is no boot menu accessible in the devices. Which means the only other choice is to use a usb connection to a PC to perform all tasks, i.e. create a rom system image backup of the working device, then use that to restore the system onto the soft-bricked one.

So is there a way to revive the s/bricked device with a rom image of the working twin?

The long story:

After using the super-sume app, my device got softbricked. Phones of my type are uncommon and are therefore not worked on by the android hacker community as much as flagship devices are. And little is known or discovered about them. So after doing more research, i've sadly come to know that there are other users here and there, having suffered the same problem as I. But enough about that.

As far as i've read and come to understand, i would need to re-flash the firmware to bring it back from it's softbrick issue easiest/safest way.

Though am not sure how the android platform would work. With PCs, i could restore a messed up system from a cloned image. What i need to confirm is if the firmware is separate from the OS (roms i believe) the same way device drivers are separate from the windows OS on PCs.

So am not sure if flashing firmware is enough and would need to stock rom too. Or is the rom considered both firmware and OS all in one?

I mentioned "restore from a clone image backup" because I have another, exact same model of my softbricked device, that functions still properly.

So i wonder if there is a way that i could use my working device to revive the soft-bricked one. In the sense that i would need to make a system image copy of my working one, to restore onto the s/bricked one.

What the problem looks like when starting the phone:

As for the softbrick appearance, the phone boots into the LG logo screen and is frozen there. It doesn't quite look like it's boot looping since the screen Never fades to black quickly just to come right back. It's just frozen there. This recovery mode screen is the only other thing i can get to besides the frozen LG screen: https://wcrates.files.wordpress.com/2015/03/lg-g3-recover-mode.jpg

I've come to learn (but may need correction on) that Tracfone devices are deliberately handicapped in a way i've never seen before. That is, their devices have no other boot type of menu besides the Recovery Menu (found before os begins boot) that is basically a factory reset. It just deletes all user data and resets system settings so that the phone works like it would at first when right out of the box. For the s/bricked device, that screen can be accessed, though executing that just resorts to the frozen boot screen again. If there is a boot menu to backup/restore from, clear cache, install from zip and what not, then please enlighten me. Because as i've tried everything, the tracfone-devices have nothing compared to non-tracfone-devices

So in order to install an updated rom, i may need to get into a type of system boot menu from where i would be able to select the option to install a rom or update it and what not. To some degree i assume that connecting the device through USB to a computer, one may do the same rom installation action through the PC, but it's in cases like these where i would need the help of and expert's first hand experience with such things or ways.

I don't mind if you want to leave a link to some tutorial some other guy has made that may closely related to (if not exactly) to help solve this issue. But i do prefer to get into contact with someone who i can report to with how the solution process is progressing. Mostly because me being a noob at this point of my android experience, but am confident since i've done this with pc's a lot.

I'm still trying to figure out what most of the android community speaks of when it comes to methods of backing up their stock roms and what kinds of software on PC or apps on the device are needed to accomplish a worthy backup. I do realize i'd need ADB and what other LG device compatible PC software out there. Here is a link where i think firmware files can be found, but since it's all in Chinese, i'm not sure how reliable the site is/can be. It's been about a month since i contacted some of their users. At this point it seems like they're no hope:

http://mobile.gaodi.net/Firmware-669539-1-1.html

I hope that i can find success so that i can post it up to help others who are in the same situation as me, and also for the many more who may yet fall into this situation.

Any help will be greatly appreciated.

Thanks.

Device: LG l21g (aka lgl21g) Destiny (model) by TracFone

Android: 5.0.1