Bill:
I checked with Randy and he said he would see if he could find his source for 3rd party batteries. In the mean time, he suggested that you contact his friend Leonard at
www.pocketpctechs.com to see if they could reset or repair the battery condition issue(s). They do not list an extended replacement part for your model, but maybe they have another solution. Randy says Leonard is a first rate guy and knows his stuff. Through Google, I found a replacement battery at
http://tinyurl.com/7qqqv for $42.77 but before going that far I would suggest doing a hard reset on the PPC with your charge cable connected and see if it comes up. If that works, while on power, I would see about applying the latest ROM upgrade to the device, then see if it will charge and hold the charge. I also found stuff for the 5000 series at
http://tinyurl.com/akjfk and they show both the standard and extended batteries, though the price is a little higher. I noticed that they show a special Torx tool needed to remove the cover on the 5000 series. One other option for extended battery type things is the add-on battery sleeve. I know that we used these in the past, before we all moved up to more modern Pocket PC's, so I am guessing we have a few of these we might be willing to let go of pretty inexpensively - assuming I can find them, of course. But just adding this to the unit as is probably will not fix the problem you are having. You will need to get it booted up first. Having said all this, I am sure Randy would advise that you consider getting a high resolution PPC with a more modern operating system on it before dumping a lot of money into and older machine. We like the HP hx4700 the best, but the Dell X50v is also popular. Here is a link to our page where there are reviews, etc.
http://tinyurl.com/dklpp I believe I have seen the X50v for sale at $399 or $418 if you include the WM5 upgrade CD. The hx4700 runs in the $450 - $520 range - a bit more than the Dell, but it has a larger and better screen and larger battery.
Hope this helps.