If a machine can receive downloadable content then it can have the BIOS flashed even without you know it.
From past I used to take out extened warranties on expensive equipment, so when I got a new SKY box I took out an extra 3 years. Just before the 3 years were up I saw stuff in tech forums popping up about SKY messing with your equipment (Conspiracy Theories come into play) I was told to take note of my ver. pattern & disconect the phone line a day before the warranty expires, give it a few days & a phone call from SKY about extending the warranty but not accepting it then the next day check your ver. pattern & it was different and 2 days after that the box started to "act" up. 2 weeks of that another phone call from SKY asking to extend, which the answer was no & 2 days later another ver. pattern on the box & a day later it stopped working. Left it for 2 weeks contacted SKY to cancel suscription & will be taking another subscription out with a new SKY+ box set. Couldn't do that so I told them to return MY bought equipment back to the original settings that they had changed through the Broadcast service (yes they can update your machine through that even if your phone line is dissconected) That they had changed without my consent. The SKY box was returned to the original ver. pattern within 4 hours after I told them BBC Watchdog are doing research into this & it will be taken to legal action.
Even up till a few weeks ago when I totaly ripped the SKY system out, every year when the warranty was supposed to expire it went funny for 5 days & then getting either a phone call or a letter asking if I want the warranty extending