Phone Samsung Galaxy S5 SM-G900F

I have genuine Samsung Wireless Qi pad and a Galaxy S5 Qi Charging Receiver, DLAND 0.5mm Ultra-thin Qi Standard Wireless Charging Receiver Module for S5. The pad is connected to the mains with a genuine Samsung travel adaptor EPTA11UWE rated output 5.3V 2.0A.

When I place the phone on the pad the blue light comes on but within a couple of minutes it starts to flash on and off and it doesn't seem to charge at all. I have tried charging with the phone switched on and off but it makes no difference.

What could be wrong? Any help very much appreciated

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