When you took out the little coin type battery, did you also remove ALL other power from the laptop. that is, did you take out the power cord and the big main battery, so there was absolutely NO power anywhere on the laptop???
You must do that to reset the CMOS chip.
The time not being retained, is the first telltale sign that the little coin type battery is bad.
Did you by any chance, test it while you had it out?
If tested with a digital volt meter, it must be at 3.0vdc or better or it needs to be changed.