He was eventually killed in Chasm Forge's Section 12 when the smartsuits instructed his own suit to disable its organic component. (TV: Oxygen)
Behind the scenes
Behind the scenes sources differ as to whether Dahh-Ren is human or belongs to a non-human species. The official Doctor Who website describes him as a "non-human".. Actor Peter Caulfield says in the Series 10 documentary Being "Blue Peter" that he is a human who is "genetically different".