XT1072 Bootloader Wrong Flashing! (Help Needed) (No Signal)

Hey Guys,

I made a serious mistake and tryinh to solve it for 2 days now without any luck.
I update my bootloader (using this post).
The problem is when I accendently updated it with a xt1068 bootloader.

After that I just went on and updated a rom but to find out that I didnt got any signal anymore.
There are enough posts on that and that it could be the modem file from a wrong region version.
I`ve tried updating a couple of european models of the modem, but still don`t have any signal on multiple roms etc.

I think the problem has to do because of the updating to the wrong bootloader, but having tried for over 2 days I cant seem to downgrade/replace the bootloader with
a good one. Getting the PREFLASH VALIDATION ERROR.

So guys is there a way to restore it to stock with the old bootloader etc...?
Btw I tried flashing a stockrom with fastboot but it also gives me the error image file too big.

So i`m a bit clueless now on how to proceed.

Any help is appreciated guys!

Thanks,

Alex