Hi el_chapi, I write in english following forum rules, sorry for my bad redaction.
I think that you don't follow the instructions and miss to run some points of tutorial.
Please check this (in spanish):
By the way, if you flashed KDZ lower than 1 GB, yo can connect your E987 using LG PC Suite or LG Mobile Tool and search for updates, LG Mobile Tool (please delete, rename or edit your hack hosts file), this tool start to download and install your operator's firmware.
Other solution is obtain your modem files (for E987) and replace the modem files of your installation (E977 or E975), but you need extract this files from other E987.
In my E976 (Movistar Peru) this files are:
all rwx rwx rwx