'92 S-10 electrical problems?????

Drove my '92 S-10 4.3L 2wd about 15 miles yesterday. Came back to it to drive home, and just enough power to run the dome light was all it had. The negative battery terminal had been loose, but we tightened it up and boosted it for 30 minutes and still didn't have enough power to run anything but the dome light. When I hit the brake pedal even the dome light went off but it didn't have enough to make the brake lights come on. Absolutely nothing happened when I tried to start it, no clicking or anything. Any help on this would be greatly appreciated!! Thanks!

Take battery to local parts store and have it tested. :screwy: