Complex sentence: However upon return to the Tel'tak they trigger a self destruct that they are unable to shut down (since Carter and Teal'c are still imprisoned), however this is revealed to be another of Boch's mind games, who has returned and deactivates the self destruct.
Split into simpler sentences: However upon returning to the Tel'tak they trigger a self destruct mechanism that they are unable to shut down (since Carter and Teal'c are still imprisoned). However, this is revealed to be another of Boch's mind games, who returns and deactivates the self destruct.