a close encounter of the not quite genius kind

Before I arrived:

"That's quite vintage, isn't it?" said the store guy.

This was the second place the machine been taken to attempt to get it running again.

"...We don't support vintage devices."

It was a MacBook Pro 15 inch. Intel processor. The power supply had gone dead. No little orange and green light.

This was after taking it to the nearest dealership on Sloane Square. They'd gamely tried to make it work by plugging in the newer style power leads (which won't fit, of course). They tried three.

"There appears to be something wrong with the socket on the side of the machine," they'd said.

Next stop Regent Street. The mothership. Big beams of light.

An appointment with a Genius.

Clue 1: The machine was handed over. He nearly dropped it. "Whoa, that's heavy!"

Clue 2: "It won't open!"

"No, you need to press the catch."

(fumble and confusion)

"Here, let me do it."

Genius takes a look.

"No, we don't have ones like this, but you might want to try resetting the SMC." Immediately upgrading the level of acronym.

"Is that like the PRAM? - we've already tried that," came the bluffed response.

"Er, can you make an appointment for Monday? We'll have someone else here who may know more."

"No, I'll ask someone else."

Later, I arrive and am told...

"It's dead. It was fine earlier. I don't think the battery is charging - I took it to three stores."

Me: "Let's plug in another charger."

Rummage in bag. Plug in different charger.

Green light comes on. Press power.

It starts working.

Solved.