Just in case someone else would like to save one of these old GPSs from
the trash, if it has the apparently blank LCD problem...

My unit had the symptom of no LCD display (like it was turned off), but
the unit properly beeps when powered on, and the POS LED properly
lights.

I found that the -5V LCD drive voltage had failed which causes the
contrast to be turned off. The -5V inverter is on the small daughter
PCB that is around the antenna connector on the lower main PCB.

Remove the battery cover.

Remove the battery cover gasket, then remove the 4 screws, then remove
the back GPS cover

Remove the top PCB (4 screws) and carefully unfold the ribbon cable.

Remove the lower PCB (4 screws) and pry the PCB out from the light
button side 1st, being careful not to mess up the button rubber pieces.

You will see a small daughter PCB under this PCB that surrounds the
antenna connector. This small PCB also has the beeper on it. Unplug
this PCB as this is the PCB with the -5V inverter on it.

Replace the two electrolytic SMT caps that are on either side (above
and below) of the 8 pin SOIC labeled "7600" which is a switching power
supply controller/inverter. I replaced the caps with SMT tantalums
(remember Tant polarity markings are opposite of the AL electrolytics).
Reassemble and test.

Regards to all who want to keep old stuff running :-) Craig