As a side note to the topic handle:

FCTM – Side-stick and takeover Priority Button

When the Pilot Flying (PF) makes an input on the sidestick, an order (an
electrical signal) is sent to the fly-by-wire computer. If the Pilot Not Flying (PNF)
also acts on the stick, then both signals/orders are added.
Therefore, as on any other aircraft type, PF and PNF must not act on their
sidesticks at the same time. If the PNF (or Instructor) needs to take over, the PNF
must press the sidestick takeover pushbutton, and announce: “I have control”.
If a flight crewmember falls on a sidestick, or a mechanical failure leads to a
jammed stick (there is no associate ECAM caution), the “failed” sidestick order is
added to the “non-failed” sidestick order.
In this case, the other not affected flight crewmember must press the sidestick
takeover pushbutton for at least 40 s, in order to deactivate the “failed” sidestick.
A pilot can at any time reactivate a deactivated stick by momentarily pressing the
takeover pushbutton on either stick.
In case of a “SIDE STICK FAULT” ECAM warning, due to an electrical failure,
the affected sidestick order (sent to the computer) is forced to zero. This
automatically deactivates the affected sidestick. This explains why there is no
procedure associated with this warning

Source:
NTSC Final report QZ8501 p79