OK, here's another scenario: this was the tech the well known 3rd party company said they could provide for a month. The tech arrives, and your mate sets him a practical test. He fails to impress, etc., etc.

But ... was the tech a regular employee of the company; was he miffed about the month ahead, and so deliberately made a mess of the wiring as a means of escape?

Or was he simply someone the company had brought in (in effect a 4th party)? Someone, perhaps, with a brilliant CV yet untested practical skills?

In other words, the 3rd party service provider was simply acting as an Agent.

Was your mate having second thoughts about forking out £10k plus expenses, and therefore looking for a way out? Can we be sure someone didn't tamper with the plug before taking the photo(s)?

Was a replacement tech sent along? Did he pass the test? think

What would Poirot have made of it all?

If you don't inspect ... don't expect.