If you have more than one battery and your Pleo is doing the same on both then that would be an awfully big coincidence. I don't think it is a battery issue if that is the case. However it is possible.
Is the battery charging from 3 1/2 to 4 hours? I assume you are seating the battery properly since you must be an old hand at it
If it is not charging for the full amount of time then there may be a charger issue.
If you want to try the downgrade then you can get a free .zip opener like winRAR, winzip or 7zip. Install the program and then right click the download and choose extract.
However if Pleo will not/can not stay on for any amount of time then downgrading may be dangerous.
Finally is Pleo stone cold and is the battery stone cold, the thermistor which monitors temperature may be playing up and giving a false reading. The only way to check that would be to run DinoMITE.
Hope this helps, hang in there.
