I'd wanted to post this last night, but was also sort of in a hurry and didn't search for it.
Several years ago, some really smart guys got their hands on a guidance computer(I think out of a LEM that never flew, but IIRC the CM and LEM computers were the same). They spent days working intently on it and managed to get it powered on and running the original software.
The way this stuff was acomplished was amazing, but some of the technology to make it work(like the corded memory) is-in practical terms-odd enough and obscure enough that even some computing/electronics geniuses can struggle with it.
Also, it's entirely soldered discrete components, which makes repair easy in a sense, but also means that you have huge numbers of solder joints and other places that can cause endless headaches 50+ years after the fact.
That indigo blue iMac g3 was the absolute bane of my existence when I was younger lol!
The later iMacs had their ups and downs. Steve Jobs was obsessed with passive/silent cooling almost to the detriment of systems. The original Macintosh models cooked analog boards like crazy, and things like the Kensington System Saver(which is a fan that latches into the handle on top and blows air through the top vents) were popular. The Cube was another a little later than the iMac, and all of mine(all 5 of them) I've retrofitted with base fans to keep the temperatures down and keep the power boards from cooking. The engineers knew the Cube had a cooling issue and even snuck an unused fan bracket into the base of it.
The first gen(tray loading) iMac G3s did have fans, but the slot-loading models(which I'm assuming your Indigo was-the tray loaders came in Bondi Blue, Grape, Tangerine, Lime, Strawberry, and Blueberry) had them. I have an Indigo that I think is 500mhz. My Indigo runs well, but one of the big issues too was that Mac OS 9 was an absolute mess of an operating system. No one person understood it top-to-bottom. The 68K emulator was integrated deep into the OS, which made it seamless but there were also low-level system processes that were still 68K and functioned on the emulator. Add things like cooperative multi-tasking and non-protected memory and you have a recipe for disaster. OS X runs a lot more stably on them, but these days it's hard to use anything older than 10.4.11 while IMO the iMac G3s run best with nothing newer than 10.2.8.