From my point of view and IMHO it looks like OP wanted to flash this phone "like he has done to other phones" but it looks like he thought every phone is just as easy as to watch a kid on youtube doing it, so again from my point of view it looks like the phone is not his, it must be a costumer's so obviously he's panicking because he cannot go to the costumer and say hey I couldn't flash your phone and ended up bricking it, but don't worry everybody on the forum says Sprint will replace it just take it to any Sprint store.
If that is the case and I'm right, I've been there, I understand it is really hard when you have to face the costumer, so my advice is if you already tried the official LG tools look for any mod somebody has made for that tool, like marvin's mod, you'll need to get a hold of the .cab firmware and encrypt it to .kdz (ironically the modded tool will decrypt it back to .cab, but that's the way it is) as long as you can access download mode you still have hope.
If I'm wrong and my assumption is completely out of line and wrong I apologize, it's just that I have read similar stories all over the forums and turned out to be like that. So if i'm wrong everything the previous posters have told you is right, Sprint might give you hard time if you are not under contract, but LG has to send you a replacement if the phone's still under the 1 year manufacture warranty, contact them and just don't tell them "I was rooting my phone and I broke it"
Now if what you did was change the MEID/ESN/IMEI and now can't get it back to the original one (again I'm just assuming that's what you did to get it into pageplus since it would need a verizon's Serial number) then they might not honor the warranty at all and if you can't fix it on your own, you are pretty much screwed. Also if the Serial number is in the Sprint's black list then Sprint won't do anything either.
So I think your best shot is to get a hold on the tools I mentioned and the firmware file and try that way, I'll assume you can easily find them since by reading your previous post you have been doing this for a long time and you must now what you are doing.
Worst case scenario if the phone is in fact yours and you can't fix it sell it for parts on ebay and get another one (Taking it apart and selling the parts separated is more effective money wise speaking than selling the whole phone).
If is not yours then just face the costumer tell him/her what happened and just go to Sprint and have it replaced.