Roadster Immediately Unlocks After Locking

Back around 2009 I bought a fucked Roadster.
The low mileage car was OK but it wouldn't start and wouldn't stay locked. The non starting was
met with a CAN bus fault so I decided to check the continuity of every single wire on the car.

This took 2 solid working days with a multimeter but it was worth it. I discovered 2 wiring faults where the
wires had become damaged internally causing a non existant connection. Repairing the wires fixed both issues.

However, I was surprised at what caused the central locking problem. Even to this day I don't
quite understand the workings but I do know the problem and I do know how to fix it.

Symptoms

If you are reading this, I'm assuming you have the same odd problem.
If you close the door and the boot and press the lock button on the key, the central
locking will lock everything but then immediately pop all the locks back open again.

However, if you get in the car, close the door and then press the lock button on the dashboard, the car locks.

How can this be? It must be something to do with the key or the receiver right? Wrong.
You are being mislead because of the odd way that the smart Roadster operates.

OK, So What's The Problem?

Did you know (because I didn't) that the Roadster will lock the doors on the dash button even if the boot is open?
However, if you try to lock the car using the key with the boot open, the car will refuse to lock.

It's an odd set up, maybe it's some sort of security thing. It's anyone's guess.

I know what you are thinking, the boot catch switch that tells the car the boot is closed is faulty.
Unfortunately the boot catch doesn't have a switch. It knows it is open by magic.

How Can It Be Fixed?

Turns out it's very easy and if you can't make your own repair wire, there is a place to buy one.