samsung a800 charging fault?

hi i've bought a couple of replacement batteries for my old a800 but i still keep getting battery low warnings. i'm of the impression it's a phone fault rather than battery, and that it doesn't always seem to hold charge properly or even increase charge when you try and charge it. I haven't actually run it down flat yet. trickle charging seems to make no difference, and yesterday it wasn't adding to the charge while i had the phone turned off. In use it often warns of low battery but when you close the phone, the charge returns to the meter.

what's going on? anyone else had this? is there any kind of phone reset or anything else you can recommend?

appreciate any help thanks

sounds like the power management is at fault or it needs a firmware update. You would need to have this done by a certified engineer

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