If there's a way to fuck things up I usually find it. I think it's because I do all bike maintenance in a state of rage. When someone invents a 100 year battery and fast, puncture proof tyres I'll finally be chill like buddha in more ways than just being fat.
I preferred your original reply. :-*
500 should work. I presume you've gone into the devices menu and forced it to search? Get the units as close as possible and wait patiently.
Also, double check the battery orientation. I'm pretty sure I've put a battery in backwards once in a G3 or maybe P2M, probably both.