I'd check the replacement DC-in board. If it has come from a dropped machine, they often have the tip of the broken power supply inside, when you push your power supply in the old tip causes a short and burns out the DC-in board. It could be another water related fault of course, but that does sound like it's got a broken tip in there.
I don't think there was any internal changes except for the warmed over processor. The teardown comparing prev rev & the new server version
I can't see anything leaping out as being different.
The power supplies in these though are the same for both 110 or 220v, so plugging into 220v should have no ill effect (we do it over here in the UK everyday...). They are known for their weak capacitors though, so the extra voltage probably finished them off, one of ours here went pop & bang with a power surge two years ago, unfortunately it needed both the power supply & the logic board.
That's the complete assembly from a G3 iBook which won't fit. The LCD inside it 'should fit', but those early translucent G3 iBooks used an IBM screen which isn't as bright as the Samsungs used in the later G3 & G4 iBooks. You want either IF183-026 which is the complete assembly, or IF150-052 which is just the LCD panel. Despite what instincts may tell you, fitting just the LCD panel, is a lot easier than replacing the whole top assembly.
If you've bought it from iFixit, then you need to take this up with iFixit directly, see
for details. This isn't the place to deal with this. If you bought it elsewhere, then you need to approach the company you did buy it from.
It's not the inverter, if that failed it would still boot normally, just with a black screen. As it is ramping the fans up that is the logic board entering CPU protection as it isn't booting, but as the screen is staying black, would say it is due to a failure on the logic board.
What install CDs have you been using? The mirror door G4s are a fussy set, will only boot from OSX 10.2.2(approx and above) CDs, not OS9 CDs (even the dual boot models). If the machine is booting, check the machine can see the CD or DVDs ordinarily, if it isn't the optical drive has probably failed. The last few of those I've looked at I've had to put a new DVD drive in them as the laser had failed.