  Genesis within the Horndeski theory is one of possible scenarios for the
start of the Universe. In this model, the absence of instabilities is obtained
at the expense of the property that coefficients, serving as effective Planck
masses, vanish in the asymptotics $t\rightarrow -\infty$, which signalizes the
danger of strong coupling and inconsistency of the classical treatment. We
investigate this problem in a specific model and extend the analysis of cubic
action for perturbations (arXiv:2003.01202) to arbitrary order. Our study is
based on power counting and dimensional analysis of the higher order terms. We
derive the latter, find characteristic strong coupling energy scales and obtain
the conditions for the validity of the classical description. Curiously, we
find that the strongest condition is the same as that obtained in already
examined cubic case.
