I'm sure this has been asked many times before, but even after a bit
of searching I couldn't find any answers.

I'm trying to identify a few surface mount components, one or more of which
may be defective. I haven't desoldered them yet, since it helps to know
what a component is before testing it.

First, there's two transistors or fets, both SOT-23 packages, one of them is
labelled "2301" or "230I" and the other one is "BR" and "D7" the D7 is written
vertically in small letters following the BR.
The same circuit also has another SOT-23 device designated as U4 and labelled
"N630". I'm assuming this is a 3-pin voltage regulator of some sort. Finally
there's a diode, black rectangular, a bit smaller than an SMA package,
labelled "3432". All of these are part of the same power supply / battery
charging circuit of a portable device that happened to be plugged in to its
charger when a lightning storm struck. The rest of the device still works, but
the built-in battery won't charge anymore, it just keeps getting lower and
lower.

Is there any hope in identifying these parts or am I pretty much out of luck
when it comes to SMT components? Is there a cross-reference anywhere?
--Tom.