Hi Ross,
It does sound like your Controller's +5V supply has been disabled.
Unfortunately, I don't think there are any user replaceable fuses inside the controller, but the attached picture of the VEC500 circuit board clearly shows a zero Ohm resistor
(circled in yellow) which may be designed to act as a fuse, and I'm wondering whether this could have been overloaded somehow by the contactor wiring.
If you are concerned about voiding your warranty by removing the cover, contact your supplier first and explain the situation.
Check out
this thread for a similar failure of a VEC300 controller.
My other concern is the way your contactor was wired
(albeit exactly as per their "WITH CONTACTOR" diagram). If the pink wire is permanently connected to Battery +, the controller would continually receive battery voltage through the pink wire even when the contactor is switched Off. This does not seem to make sense to me as the pink wire is used to activate the controller, therefore the controller could possibly be permanently activated when it is wired as per the "WITH CONTACTOR" diagram.
I would have thought the pink wire should be connected to the the switched side of the e-lock connector to ensure the controller is completely disconnected from the battery when the e-lock is turned Off.
The diode may be required to prevent any voltage spikes produced by the collapsing magnetic field in the contactor coils from reaching the controller when the e-switch is turned Off.
However, if the VEC controllers do have some form of precharge circuitry which is reliant upon the battery feed to the pink wire, then this configuration may not work properly.
With the original wiring, when the contactor is Off, the main battery + supply would obviously be disconnected from the controller, but I'm now wondering if the controller might be able to pull current via internal circuitry
(or possibly an integrated precharge resistor?) connected to the pink wire when the throttle is moved and
(if my suspicions are correct) the controller
is permanently activated.
Perhaps the zero Ohm resistor has "blown" on both controllers, and is now preventing them from being activated.
If the controllers are no longer able to be activated, that would explain the loss of the +5V supply.
Alan