There is no evidence that anything got inside the serpent to make it do what it did. Paul says the serpent "beguiled Eve through his (own) subtilty" (2 Cor. 11,3).
The previous text is in English. Here is a translation to Czech: Neexistuje žádný důkaz, že by cosi uvnitř hada nutilo tuto bytost dělat to, co činila. Pavel říká, že had "ve své lstivosti oklamal Evu" (2 K 11,3).