That could be true but it would be ludicrous , there isnt a big red switch or a 3 pin plug that youcan turn off/pull out on these things.
If something like that happened what does it say for BA security and risk management thata low level contractor can shut down the entire airline with one mistake or maybe even deliberate act. farcical. Any mission critical facility of that scale and class should never allow one individual workign alone , especially where complex or HV power is involved just for safety reasons let alone business protection. How does the business know that one guy isnt , drunk, drugged, dumped by wife /girl. Facing a disciplinary, bribed, malicious etc etc etc A complete joke