[Sprint LG Optimus G] iunlock:
I was having a lot of the problems mentioned by the OP. Here's my situation:

Got the new phone, LS970.

Rooted, SU, Busybox etc...SUCCESSFUL.

Flashed the stable CM Rom, "cm-10.2.0-ls970.zip."

Then I had realized CM (custom ROM's in general?) don't recognize the code entered in your dial pad to activate with the service provider. (I'm with a provider who use Sprint's network. MVNO.)

So I had to revert back to bone stock, which is when I started to experience the nightmares with using the FlashTool, LGNPST w/ TeenyBin etc..

I couldn't get the flash tools to work properly for 3 days straight and it was driving me crazy. From boot loops to not being able to even get it into Download mode...I was about to pull my hair out.

I finally got it back to stock using LGNPST with the correct .dll file along with "LS970 Original TeenyBin[ZVBin]," This was the only .bin file out of the three listed on that thread that worked. With the other two I could not boot back up and could barely get into Download mode.

After successfully activating the phone to my carriers network, I rooted and flashed the stable CM Rom.

Then disaster. It would go into the stock recovery screen (black with blue letters on top) and although there was a menu there I could not select anything by pressing power. The volume buttons would just highlight the options, but pressing power did nothing. So I had to long press the power button to shut it down and after many attempts of trying to flash it back to bone stock using LGNPST, only the .bin file mentioned above worked for me.

I do not want to remain on the bone stock rom, obviously. But then I knew that by flashing any ROM would throw my phone back into this chaos. As I was browsing through the stock phone trying to figure out why I was getting the screen of death (black w/ blue letters where the power button didn't respond to any of the options) I saw something interesting...

File Manager -> /storage -> sdcard0 -> I can see all the usual files and the .zips that I put on there...

BUT THEN...

There is a folder called "0" ...when pressed, I can see almost a duplicate of the files that I saw in the main "sdcard0" with the exception of now seeing all the other .zip files that I had put on there from the previous attempts of flashing.

Burning QUESTIONS:

WHY IS THERE A DUPLICATE FOLDER WITH OLDER STUFF IN IT CALLED, "0" ???

I know that it's a folder called "0", however, could this be some kind of a partition issue?

COULD THIS BE THE CAUSE OF THE BLACK SCREEN OF DEATH W/ BLUE LETTERS & a DEAD PWR button that doesn't do anything?

What could have caused this duplicate folder? I've noticed CM based ROM's to create a "0" folder? Why?

So now I am wanting to correctly partition it back to bone stock. As I am OCD with reading as much as I can thoroughly before doing anything, upon hours of searching, I have come across something interesting that I will try to see if this fixes this duplicate folder/possible partition issue. Here's the post.

I'm pretty sure what I have explained with there being this weird duplicate folder is the cause of the walls I'm hitting when flashing a new ROM.

Any help would be greatly appreciated.

OP, check to see if perhaps you are experiencing a partition issue?