It went wrong all by itself
Remember British Satellite Broadcasting (BSB) and their Squarerial (The square shaped satellite dish), a long since merged/defuncted UK corporation was using a VAX 11/785 in the development of this failed product (This is a whole story by itself in marketing pushing bizarre requirements to an engineering team) - The VAX 11/785 had been taken off contract as they had a lot of bright engineers and they would self maintain to save some money. So all seems quiet/good for about 8 months and we get the call, can we come to site the VAX 11/785 is borked and they need assistance (Which we will charge on a T&M basis). I arrive on site ask for some background as to what has happened, get basically a story that everything was good they had a problem but this problem quickly moved to a complete system failure. They had done some diagnostics but not touched the VAX physically.
The VAX 11/785 was switched off (Weird, not normally switched off, even when a fault is present) - Asked why it was switched off - They said they could not start the machine - The VAX 11/785 had a cutdown PDP that was the boot controller, so you would normally have this active even when the main machine had major issues.
So, my first action is to open the main cabinet door to look at the logic boards (The VAX 11/785 CPU was basically a set of logic boards connected to a backplane) - Opening the cover to the logic boards I asked again if they had done any "hands-on" troubleshooting - They said no, no-one had touched the machine at all.
So I said that was strange as one of the Logic Boards was inserted the wrong way round (Top was on the bottom rail) - This would have taken a lot of effort to do as the boards were keyed to go in easily one way only (i.e. with top of logic board aligned to the top).
Cue a lot of people suddenly looking guilty - They fessed up that they had taken the cards out to reseat them as they thought that may resolve the problem, they had a problem with one card being difficult to get back in, which in fairness was an issue with this enclosure - They thought the card was in the wrong way so flipped it an re-inserted and with what I can only assume was superhuman strength managed to get it all the way in.
It took some effort to prise the card out and peering at the backplane revealed crushed pins on the backplane.
So 2 days later, new backplane, assorted new logic boards and north of £35,000 they were back in business (let alone the business cost of not having the system up and running). They basically they had to spent about 8 years worth of the maintenance contract that they had cancelled in one go.
Their management did try to say that it was easy to make the mistake and it was our fault that this was possible (Negating what I can only assume was obvious visible guides not to do what they did, but the sheer brute force needed to do it). But sanity did prevail and they paid the bill and even put the system back on maintenance contract.
Alas th Squareial did not help the company make the expected millions (Especially as told to me by one of the lead engineers the spec they were instructed to build it to did not factor in cloud cover .... So in testing/demo phase all was good until it got cloudy - so expense re-design required) - And BSB got bought by Sky to become British Sky Broadcasting and the Squareial was consigned to the dustbin of "what were they thinking".