Watch the full 2020 reboot episode with English subtitles to see the ancient war backstory unfold:
: Attempting to defend Izzy, Tentomon digivolves for the first time into his Champion form, Kabuterimon , and uses his "Electro Shocker" (Mega Blaster) to destroy the Black Gear controlling Andromon. Digimon Adventure Episode 5
Izzy (Koushiro) wanders off to investigate the machinery and finds a secret room with a large power source. Watch the full 2020 reboot episode with English
The reboot episode takes a more lore-heavy approach, focusing on the history of the Digital World and the underlying conflict. : Digimon Adventure Episode 5