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@outwithspam
Alternate. Here we suppose you have at least T (Target-mode) accessible on your mac & there are no firmware password installed. Poweer on, press & hold T until yuo'll see FireWire logo on screen. Release buttons & press CTRL-ZZ (NOT CMD!). This will drop you to OF shell. Here you can do all you want if know how :) (reset-nvram & reset-all & boot from some device & so on).
 
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