I've been able to build a complete LiteCell BTS firmware image from the h
ttps://gitlab.com/nrw_noa repo with Yocto and load and run it successfully on my LC1.5. I believe going this path may void your warranty, but I am not sure. I had better luck with the BTS version than the nitb or bsc versions, although I was rushed for time and didn't take much effort to attempt to debug those builds. There are good instructions for generating the bts binary here:
https://gitlab.com/nrw_noa/lc15-bts-release-manifest/wikis/home