Why go through that device-breaking battery dance when you can still get a BL-5J battery pretty much everywhere?
Booting from an SD card, while possible, is rather impractical on N900 because it gets disconnected whenever you open the back cover.
The N900 that lays next to me right now still works as a phone. I have to replace its screen though, as recently it took some damage in my pocket and got a small crack in its bottom middle. Touch still works perfectly though, so I'm not in a hurry :D
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