Dave W wrote:
After re-celling, surely the battery management IC will need
re-initialising via a serial link? And it may have been 'finalised' to
prevent this, unless the flash memory is removed from the board and
wiped before replacing?

It depends on the battery - the management IC may store parameters in SRAM,
so they're cleared when you disconnect the cells. Or it may provide a means
to reset it. You should check this up before ordering replacement cells.
(the chip may well be a standard one from TI etc)

I investigated an old HP laptop in which I had replaced the battery.
Probably not a good one as after the first charge it failed. The
supplier replaced it suspiciously quickly without question, but the
second one only lasted a couple of years.

That seems to be a not-uncommon aftermarket battery experience

Theo