I think I'm actually missing something here still. Everything I read suggests I need to boot into recovery mode as a first step, and that I ought to be able to do that by holding down the "home" key while I'm starting up. Instead I get a bang (!) in a triangle icon with a phone next to it.
Have I skipped a step or is there something wrong with my phone? I know there's something wrong with my phone ... that's why I embarked on this project to begin with. But could that be some how preventing me from booting to recovery mode? Or is the problem a skipped step?