A misaligned AI can't just "kill all the humans". This would be suicide, as soon after, the electricity and other infrastructure would fail and the AI would shut off.

No. it would not be. In the world without us, electrical infrastructure would last quite a while, especially with no humans and their needs or wants to address. Most obviously, RTGs and solar panels will last indefinitely with no intervention, and nuclear power plants and hydroelectric plants can run for weeks or months autonomously. (If you believe otherwise, please provide sources for why you are sure about "soon after" - in fact, so sure about your power grid claims that you think this claim alone guarantees the AI failure story must be "pretty different" - and be more specific about how soon is "soon".)

And think a little bit harder about options available to superintelligent civilizations of AIs*, instead of assuming they do the maximally dumb thing of crashing the grid and immediately dying... (I assure you any such AIs implementing that strategy will have spent a lot longer thinking about how to do it well than you have for your comment.)

Add in the capability to take over the Internet of Things and the shambolic state of embedded computers which mean that the billions of AI instances & robots/drones can run the grid to a considerable degree and also do a more controlled shutdown than the maximally self-sabotaging approach of 'simply let it all crash without lifting a finger to do anything', and the ability to stockpile energy in advance or build one's own facilities due to the economic value of AGI (how would that look much different than, say, Amazon's new multi-billion-dollar datacenter hooked up directly to a gigawatt nuclear power plant...? why would an AGI in that datacenter care about the rest of the American grid, never mind world power?), and the 'mutually assured destruction' thesis is on very shaky grounds.

And every day that passes right now, the more we succeed in various kinds of decentralization or decarbonization initiatives and the more we automate pre-AGI, the less true the thesis gets. The AGIs only need one working place to bootstrap from, and it's a big world, and there's a lot of solar panels and other stuff out there and more and more every day... (And also, of course, there are many scenarios where it is not 'kill all humans immediately', but they end in the same place.)

Would such a strategy be the AGIs' first best choice? Almost certainly not, any more than chemotherapy is your ideal option for dealing with cancer (as opposed to "don't get cancer in the first place"). But the option is definitely there.

* One thing I've started doing recently is trying to always refer to AI threats in the plural, because while there may at some point be a single instance running on a single computer, that phase will not last any longer than, say, COVID-19 lasted as a single infected cell; as we understand DL scaling (and Internet security) now, any window where effective instances of a neural net can be still counted with less than 4 digit numbers may be quite narrow. (Even an ordinary commercial deployment of a new model like GPT-5 will usually involve thousands upon thousands of simultaneous instances.) But it seems to be a very powerful intuition pump for most people that a NN must be harmless, in the way that a single human is almost powerless compared to humanity, and it may help if one simply denies that premise from the beginning and talks about 'AI civilizations' etc.