This may have been addressed. But I thought I would throw this out there before you unload that "male".
First of all, you said you popped him. Did you see definite hemipenes? Or did you see mature female scent glands? And when you say "sperm" are you seeing sperm plugs OR dried female mucous "stuff"?
This is not meant to sound as retarded as it does. But I have pulled so called "sperm plugs" from my proven females just to prove this point to others. Of course, they are not sperm plugs. But that's what many people would have assumed they are. Those with experience, obviously know the difference. But this was your first try at this and you don't have a frame of reference.
Popping a 1,000gram ball for your first attempt could be a little misleading. Sometimes it easy with an adult male. But most times, by the time they are that size, popping is not always that easy. So maybe it's a girl and you mistook a couple of signs. I am just telling you thins as a hope that you still have a girl. You never know. Doesn't hurt to have someone with experience check him/her. Of course, if obvious hemipenes popped out, then never mind.
As for the person who sold you this animal. It's possible that it never popped for them. It happens all the time. Usually after a few tries, if it's a male, even the suborn one's will pop. But if you never doubled checked and 1 1/2 years has gone by, it's not fair to totally blame the seller. If you had popped him at a few weeks or months then that would be different. Maybe give the seller a chance to trade you outright.
Another thought. It seems that older normal females are much more reasonable in price now. So you might still be able to get up to speed this next season with a smaller investment than lets say, last year.
Troy
