Day 2 of 007 "Cold Finger" ta da daaa...
Met up with a keen mate of mine who likes to tinker and we made good progress. A bit of a nasty hack to be fair, but it's just a prototype so far. The space between the sensor and the circuit board is very tight, and I'm sure I heard something crunch when wiggling the cold finger in.
Then next gotcha on the 1100D is that there are screws for the sensor retaining plate that need to be circumnavigated or drilled for. To make it even more tricky, the main PCB is U-shaped and fits around the sensor, so it's necessary to make a 90-degree bend outwards at the same point in space. We prevailed in the end, but it's not pretty
After all that hacking, I was pretty convinced the camera would be dead on reassembly. After refitting all the ribbon cables and internal screws, we hooked it up to power and the laptop and lo and behold it powered up, connected and took a very red tinted image

Lots learned and a v2 is practically a certainty.
One issue with the image is that there is a regular pattern of vertical lines. Could this be the grounding issue, or have I borked it somewhere? So far, I've haven't grounded the cold finger, but it was getting late and I'll start afresh tomorrow. Still in shock that it worked at all