I had to fill up some gas since the tank was almost empty. I realized that the button on the driver's door would not work to open the fuel door. So I decided to open the trunk and to figure out what I could do, but then the trunk release button did not work as well. The trunk release button works with the remote.
I have a 1998 volvo s70

 

I believe there is a pull lever in the trunk to pop the fuel door open. From the sounds of it, you are not getting power to the trunk and fuel door buttons. It is possible the bottons went bad.