[Q] Soft Bricked my Galaxy S4 I545/Can't flash stock ROM!

Last night I was trying to flash a custom rom on 5.0 or 5.1 lollipop(i forgot) on safestrap from 4.4.2 kitkat. But after doing so, and going through the flash menu, I then rebooted and the samsung boot logo came up and froze. It then rebooted itself and goes into recovery mode.

And while in recovery mode, the info in the left corner said that the version was
I545VRUFNK4.


Also I have tried flashing back to the stock rom and This is the error I get when I flash my the MJ7 stock rom(Or pretty much any other stock rom I've tried for i545)

<ID:0/007> Initialzation..
<ID:0/007> Get PIT for mapping..
<ID:0/007> Firmware update start..
<ID:0/007> SingleDownload.
<ID:0/007> sbl2.mbn
<ID:0/007> NAND Write Start!!
<ID:0/007> sbl3.mbn
<ID:0/007> rpm.mbn
<ID:0/007> aboot.mbn
<ID:0/007> FAIL! (Auth)
<ID:0/007>
<ID:0/007> Complete(Write) operation failed.
<OSM> All threads completed. (succeed 0 / failed 1)

After trying and trying to fix it, the screen eventually goes into the "This firmware upgrade has encountered an issue. Please select recovery mode in kies and try again."
I've been looking for answers all day and last night but I haven't been able to find one. Recently, what I've found is that theres a possibility that I'm stuck in the NK4 bootloader or something? and that I need to flash that same firmware on the same version im on? sorry if I don't know that much.
I really need help fixing this because I've tried so much and I would love to hear some of your guys advice. Thanks.