How do i replace the HP Probook 4520s CMOS battery?

[Douglas73]

The HP Probook 4520s CMOS battery needs to be replaced - where is it and how do I replace it? Thanks

[Huffer]

RTC battery 449137-001

See p. 96-97 of the Service Manual here:

Manual 

The battery is a CR2032 you can probably buy at CVS with the hearing aid batteries. It's a bit of a slog to get to, but the Manual will take you through it. Good luck. 

Please accept as solution if this is the info you needed. 

[Douglas73]

I saw the manual - I guess I did not get down into the weeds far enough to see the procedure.  This is not my machine - I'll have to ask if they REALLY wand it back (I am not a pro, but willing to try) as I may have too many pieces left over.  Thanks for pointing me in the right direction.