The link at step 1 appears to be just telling me to force switch off using the power button & re-start? I did this last night & then left it off all night (NB; I'm in the UK; it's around 10am now). I'll see how it goes this morning.
Otherwise Step 2 is another language to me I'm afraid...! 'wired peripherals' - do you mean hard drives? 'aftermarket expansion cards' ?? No idea what this is, nor 'FileVault', & I have no idea if 'the boot volume is a software RAID'? The Mac is as it was when I brought it from the shop; I haven't added anything to it, if this is what you mean? Sorry; I'm pretty adept with computers but this technical language escapes me - apologies...
The link at step 1 appears to be just telling me to force switch off using the power button & re-start?
No, there's more to it than that. I don't think I can explain the procedure any more clearly than the support article does.
Any external device that plugs in to the computer.
aftermarket expansion cards
Not applicable. The rest isn't applicable either, if you don't know what it means.