Powerbook G3 Pismo Help

Hi all,

A client brought me a black Powerbook G3 which I believe is a Pismo
because of the bronze keyboard and reset switch near the modem jack.
It does not power up at all and the green led doesn't even turn on. I
have tried several different batteries and ac adapters (all of which
worked on other powerbooks) so I have narrowed it down to the laptop
itself.

I have tried all combinations of power adapters and batteries in and
out with no change in behavior.

The power jack itself is not loose and when I plug the power cable in
and put my hear close to the keyboard I can hear a very high pitched
whine that goes away if I pull the plug out.

I have reseated the daughter card (no change).

I suspect the PRAM battery, but am unable to verify whether this
no-start condition (you'd think the led would light up), is sympotmatic
of this. I'm hoping I can find a PRAM battery locally.

Any suggestions? I'm a hardware gut so dissassembling it further to
repair it (if parts are reasonable $$) doesn't phase me, but I'd like
to make sure I'm barking up the wrong tree before I break out the
tools.

Thanks,
Chris