Installed new battery charged overnight in each of my cradles. still shoes nothing on screen.

Some batteries may require up to 24hour charge cycle before functioning, when the handset is on the base do any lights illuminate?

If you have a working handset I would try charging that on the base unit - you may have a faulty power adapter or cradle, not the battery

Cradle and contacts are fine. Cradle circuit is nothing but a reed relay and few wires, relay closes on proximity to robot's body, therefore no voltage on contacts before robot is close to cradle.
There is a thermistor inside of battery, and mine was bad. I removed it and now I am charging the battery from my bench power supply at about 220 ma current, overnight, and it works. Probably the solution is to get a new replacement battery, but the one with the thermistor inside (OEM), easily recognized by the third wire, and all should be fine, assuming that nothing else is wrong with charging circuit or power adapter (12v/1A)
Hope this will give you some ideas of where to poke.
Once successful, please post your solution.

Make sure the battery is inserted correctly in the cordless handset and that it is left on the charging cradle to fully charge overnight.

If the battery still does not power the phone even after charging, then the battery may be permanently depleted. Try buying a new battery for the unit. Be sure to fully charge the new battery as well before using.

Good luck.

Is your new battery charged? You may need to place it in the charger or hook the camera to the AC power and leave it overnight. If you have a charging cradle try to charge the battery that way. Sometimes that arrive dead.

Yes. You need a new battery. I would assume the same. Have the battery checked or try charging it in the battery charging cradle overnight.

I will be writing off the PDA as it is now over three years old and updating to more recent technology. I have not yet made my repalcement choice.

I would guess that the battery is not being charged. The problem could be poor connections between the charger & Camera or between camera and battery; or the battery no longer will take a charge.
First, clean the connections with the eraser end of a pencil. Clean the connections on the Charger and on the camer; clean the battery connections and in the camera, Charge overnight. If this does not get the camera working, borrow a battery and see if this works.

I think its probably your only choice, NIMH batteries are known to have a very short shelf life if not regular charged / discharged you can get GE cordless batteries here - GE Cordless battery

As I understand it, the basic cradle that comes with the Compaq Ipaq 3870 does not charge. If I were you, I'd either seek out a charging cradle or google the instructions for modifying your cradle to charge. Good luck...

Make sure that battery is properly in place. Somertimes it will charge in the cradle but not actually charge if the battery is loose or not seated properly.

OR

Time for a new battery