Thank you Jonathan. Here are some pictures for reference:
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Are the IGBTs the 3 pin components with a small heat sink? I was vaguely expecting 4 pins but am no expert.

To get to the DC bus I guess I need to get to one of the big capacitor pins? There are 2 boards stacked on top of each other with the top one looking like the high power side and the bottom one looking like the control/software side.

It looks like quite a job to take the top board off to get to the pins since they've soldered multiple pins in place around the edge of the boards to hold it in place (or prevent tampering !).

I'll have another look, but most likely going to send it away.

Found this article quite useful . . . .
The ABCs (and 1-2-3s) of variable frequency drives | Motors/Drives content from Machine Design