[rob74]

Well yeah, GP's argument applies here too: whatever engine you insert into your Honda Civic will be the Civic's engine, so the statement would be correct - as long as you specify that it's the Civic's engine and not the Civic engine (as in the original one).

To be less academic: I don't think there is a mouse in this world where you can actually modify the firmware, because using flash memory for something this dirt cheap and with a functionality that hasn't changed for decades is out of the question, so this is probably the only way to do it...

[Piskvorrr]

Pretty sure that the multi-modal wireless mice (think Logitech MX Master) have a firmware for the mouse and a firmware for the receiver.

(how I know: I managed to softbrick one - and reflash to working condition.)