Looks like a machine that was cared for once upon a time!
Somebody splurged out for the 030, extra hard drive and then one day it was relegated to some dark corner and forgotten about
How far do you want to go bringing it back? The whole lot needs stripping down. PSU is more likely dead, could be a fuse or bridge recitifier and then failed capacitors... I am no expert on things like that mind! But I do know that even a fubard board will power up and just sit there doing nowt, coloured screens etc.
Rust is a pita! In the USA there is something that is amazing for cleaning rust off corroded metal in minutes called Dr X. Typical I cannot seem to get it in the UK, all I can find is the usual stuff that takes ages and never truly works 100%.
I did find Evaporust which does a dam good job mind! but with anything rusted, after it is cleaned it will rust again so needs protecting. I also noticed the chassis on that 2000 looks like one I have here, it is boggo grey coated steel with the beige paint on! My other 2000's are galvanised and they seem to fair better when it comes to resisting rust.
I think if there was ever a time for a re-created Rev6.2 A2000 motherboard then it is now! 2000's really suffer from those sodding batteries! I have a pile of boards here only fit for spares because of those things.