1989 riviera wont crank

The car was in storage shed through winter months. Now the battery goes dead after a month of non use. new battery 3 months ago. Dead battery is an occaisonal occurence. When the battery is OK, sometimes it just won't crank and everything on the dash goes blank. Towed it to the shop and the mech. found corrision at the battery/starter connect. That was 3 months and the problem is still with us. Security system was acting up before storage in that lights and horn would activate for . no apparent reason, ussually at night. I hope this is enough info. to get a few ideas from anyone with a little knowledge about the breed.

try checking the dual positive term set up. remove the long bolt and take it apart there is a lead spacer in between the 2 connectors that corrosion builds up on it may be causing a bad connection