FBC tuners not plugable/not replaceable - I guess only by Impex-sat/Gigablue (Germany)
So if you haven‘t done this:
Connect cable to input A - make sure its A
Flash with ImageManager latest image into another slot.
It will reboot and go into wizard setup
Do NOT use settings backup, but setup from scratch and see if finds the FBC tuner - if so just configure tuner A and then run a transponder scan to see if it finds anything.