When I have the daughtercard plugged in, I have a short between ground and +5V when measured with a continuity tester. With the daughtercard out of the computer, can can test the card for continuity between edge 5 and 3 and it's pretty steady. I've sat there for at least 30 seconds with continuous tone.
Are you actually measuring a short (around 1 Ohm or less), or the parallel addition of the many 220/330 Ohm termination resistors that sit between the 5V supply and ground? I suspect the latter. You can do the mathematics on it, but I expect you'll normally see something in the order of 10 to 15 Ohms between ground and 5V.
If you're tying to repair the RTC, look at the
guide I wrote on the subject. It's specifically for the A4000D, though in the A3000 the circuit is practically identical.
