FunBike31Its not always just a disconnected cable, sometimes the cable is torn so a replacement is needed, rarely even broken connector.
Hi thousandth user without SIM1 or fingerprint reader
Due to slight long-term bending by putting it in the trouser pocket or to a shock, even small, 25-30 cm is enough, the cable connector is no longer connected.
With a lot of luck, a strong press on the location of the fingerprint reader (on the back of the phone) is enough to restore contact
Otherwise, you have to open it, reconnect the cable, close it and then recalibrate
Below is the best discussion for this common problem.