[drmadison]

I always removed the power cord. And I doubt it's as simple as DIMMs sadly.
The machine won't come up (even with the jumper in place) - the PSU looks like it's trying to come to life when first plugged in but immediate drops down and only draws idle standby power of ~4watts. My current guess is the O2+'s logic board or frontplane have a short on them that damaged the previously good components when I tried swapping them in for diagnostic purposes, which then fried something in my other O2. Unlikely sounding given the PSUs look clean and no visible signs of damage on anything (burnt traces, pins, anything like that) but it's the best theory I have to go on right now... Unless anyone else is aware of reasons an O2 wouldn't power up, even with the power-on jumper in place (when it was functioning fine the day before).