truck wont start or even hold a charge on 1994 Chevrolet Suburban 1500

after trying to connect stereo wiring in my truck the battery died. the alternator was just replaced a few days before so i bought another battery but it drained rite away, it wont hold a charge or do anything when we try to jump it. the battery gage and the RPM gage arent working either, what could be causing this?

Asked by for the 1994 Chevrolet Suburban 1500