I'm unable to ascend

Wuji Sendra attempted to ascend after training for 1000 years only for him to fail, he is now, under certain circumstances, forced to train the son of a powerful old ally, this son happens to be a Reincarnated person from earth with a system, will they be able to get revenge on the heavens under his teaching?

Read as the kid has to constantly lie about his power and skills as Sendra earnestly attempts to teach the boy.