Receive a phone call from them, and ask for your time for the interview time.
They gave me an expression that they need an urgent engineer to fix the R&D problems, but during the interview, I feel they have no clue about the technical problems of their product, and maybe they do not care.
There are several youtube videos about their products, but no too many clicks.
Personally feel the product in the wrong direction and have great potential to grow if they change direction. I did not get the job, so it is no my business to tell anyway.
Wish them good luck.