Baden ‘A’ Type with Fishman Elipse Aura pick-up

[Mahler1911]

After changing the ailing battery in the Elipse Aura, I now have a nasty, high-pitched whining feedback, when I plug my guitar into my ‘Zoom’ digital recorder.
I have tried doing what the manufacturer says, to ‘hold down the measure button, having lowered the volume and switched on the anti-feedback switch, then raising the volume’. Nothing happens, but a flashing light and a synchronised pulse. I am unable to use my guitar for recording.

I have to admit that I am a technophobe - technology frightens me! I know so little about pick-ups, but I am very worried about this problem.

Is there anyone ‘out there’ that may be able to help? Thank you.