Given this summary of the movie Short Circuit, how can we conclude that what happened to number 5 was truly a miracle of life that manifested sentience, rather than a computer malfunction?
Short Circuit is a 1986 film about military robot that becomes sentient by lightening strike, escapes, learns, adapts, and over comes many challenges of a former robot attempting to prove its sentience to its makers and make a life for itself.  
The miracle of life that is sentience has certain markers that distinguish themselves from computers and technology, and the film attempts to showcase these via a series of acts.  First and foremost, the technology of the time period did not have any of the capabilities of Artificial General Intelligence, which is confirmed by the programmers confusion by number 5 not abiding its programming.  Given the amount of input that number 5 must have extracted, processed, stored, and analyzed, there were insufficient compute resources of the time period to support this type of live streaming, instantaneous processing and analysis.  
Johnny 5 was alive because it was able to learn what death was, become afraid of it, and fight for his ability to survive.  Johnny 5 also learned how to outwit his opponents without the use of excessive force, while also using comedy to disarm his foes.  In the end, it was able to trick his would be destroyers into believing it was dead, allowing him to escape into a life with his friends doing what he loves, reading input.  
What better proof than this, of the miracle of life, is for someone to fight for it, and live.