[rescue] Netra t1 battery?

[Mouse]

I've got a Sun Netra t1 which complains on poweron that

 WARRNING: NVRAM battery is either bad or just replaced! 

The battery is a removable thing that sits on top of another chip.
It's a little four-pin thing.  I could, maybe, find a replacement, but
I was first wondering if (a) there's more to that piece than just the
battery and (b) if not, if enough is known to replace it with an
external battery, a la the hackery people have done with the
battery-backed SRAM chips for things like the SS20.

The removable piece is marked

	  ODDXRXX5
	M4T28-BR12SH1 .
	TIMEKEEPER .
	SNAPHAT . A
	LITHIUM BATTERY

It's possible the Xs are semantically zeros; I rarely see zeros slashed
that thoroughly, though, and there's nothing on there that I am sure is
intended to be a zero.

Any thoughts?

					Mouse