|I'm assuming the battery replacement was to cure the self same problem and that the replacement has been given a good charge.|
Make sure the battery connections are sound. Otherwise about all I can think of is that there is problem with a connection from the battery to the motherboard, or even within the motherboard. You could use a voltmeter on it until you reach some component or other - then it gets tricky.
Always pop back and let us know the outcome - thanks