Thanks, Simon, I think I've got it now! I assume the red & green to the chip are +ve & gnd. Looks like the track the blue wire is connected to goes up to the connector on left on picture. So a wire to this connector is cut, the yellow wire picks it up, and the blue wire feeds it back to the pcb

I guess when I pull it apart it will be clear

Before I do this, I'd like to rotate the numbers on the km mileometer to match the mph on the broken one - 57,800 miles, so about 93,020km. Any tips on this, or would I be better just leaving it - it's currently about 183,000km.
Thanks for your help with this, Alvi