Wasn't the crew oxygen bottle serviced recently? A slow leak, oxygen build up, and then an arc in the electrical bay setting it off could lead to an intense but short duration fire or explosion that breaches the hull. Those small ARINC 429 cables carrying ACARS and other data would be first to go. (When those cables go, you can not tune the VHF or HF as the control heads are ARINC 429 connected, so no communication is possible.) Minutes later, the transponder cables burn possibly.
During the fire and hull rupture, the crew is trying to figure out what happened, turning back to base as they enter hypoxia. Fire goes out, the tough T7 flys on to the Indian Ocean.
https://www.youtube.com/watch?v=SyaWdb1GPJM