Nevermind the error. It was just to see if the phone coupled with the card and switched to continuous active reading at full power.
Well, it looks to me like the bullseye has gone open circuit, and the reason why you see a single blink is because the cellphone “sees” the smaller load of the blinkies (which have their own smaller antennae) and tries to get a read, but can’t, so it goes quiet. If the bullseye coupled and responded, the cellphone would do what you observed with the credit card.
The reason I asked you if it blinked again after a few seconds is because the phone should retry to select something in the field actively. I’m surprised that it doesn’t, but maybe your phone has one of those chips that puts out weak probe pulses to detect things coming in and out of the field.
In any case, I’m fairly sure the bullseye has gone dead, sadly. Maybe someone on the forum can shed more light, but personally I can’t think of any other explanation that fits the symptoms you describe.