K, I got the HTC Hero, around two or so years ago. I loved the phone but could not get the back off. So I couldn't access the battery or the SD card. And I was not alone with this problem, check online tech support sites and look for questions about the HTC Hero and the top question is how to get the back off.
Well I finally got it out, turned the phone off, placed it screen down on my left palm, put the right palm on the back and pushed away from the USB panel. You have to push hard and will hear a click, and then you can just pull it away.
That took almost two years....I am full of fail.