Your description of imaging is true for functional mapping. However it is not true for reverse engineering. You're missing fine-grained data over time. In both neurons and computers state changes happen millions of times per second. For example, in a neural field of a million neurons, many firings occur multiple times at un-synchronized intervals The best thermal imaging can capture only a handful of state changes per second. Thus it is missing the vast majority of fine-grained activity over time, which is essential to reverse engineering the processes occurring (as opposed to merely mapping function).
Other biological imaging techniques, such as NMR and MRI, are geared to plotting fine detail, not short time intervals. In your computer thermal example, there is no faster non-intrusive imaging technique, e.g., no NMR, etc. The next step is intrusive logic tracing, which requires direct connection to individual chips in the processor, or individual gates in a chip. We have no equivalent for those techniques in biology.
Thus extending biology's imaging processes to a computer is invalid.