I think the point of GP's comment, though, is that it's arguably straightforward to bootstrap some degree of electricity generation without there necessarily being a working energy supply chain (e.g. building one's own dynamo with a magnet and some wire and hooking that dynamo to a windmill or watermill or steam engine or other turbine, or salvaging bits and pieces of broken solar cells to build a new one from almost-scratch; then it's just a matter of building capacitors or batteries or flywheels or elevated weights or whatever to store that electricity). Yes, it'll be absolutely painful (and will offer nowhere near the energy production/distribution capability to which we're accustomed as a society), but it's survivable.

It's also possible to bootstrap some degree of computing power without an electronics supply chain, but it's also much easier to cannibalize from existing devices (whereas for the current energy supply chain there are fewer things to be cannibalized, besides perhaps electric motors to turn into impromptu dynamos).

Realistically, both will probably go hand-in-hand: we'll use primitive, cobbled-together generators to power primitive, cobbled-together computers; which we'll use to control more sophisticated generators to power more sophisticated computers (and the more sophisticated processes for repairing/building those computers); and so on until we're eventually back to where we started.