A terrible PhD situation in Germany. Please help
It is not uncommon that a German professor does not give advise to their PhD students. Neither is it uncommon that the 2nd referee does not want to read your thesis. In Germany, whether your dissertation is good enough or not is mainly decided by the first advisor. If they say it's ok, then it's ok. Your advisor theirself is the chairman of the exam committee, the other members would not say "no" to him.

That is, there is no need to worry about your situation.

If I were you, I would just write up my dissertation, give it to my advisor, and ask them for advice. Then, from what I know, the advisor would find some time to read it, and tell you something to improve (they have to pretend as if they understood your thesis). Then you could do the improvements, mail the thesis to the 2nd referee. Again this guy would also tell you something to improve, you do it, and that's it.