Check and see if your battery is dead. If it is, charge it. You probably have some sort of drain on the battery as opposed to a short.
After you charge it you can test each circuit at the fuse panel with the amp function of a multimeter. There are are several good posts on how to do this - search on "battery" or "dead battery."
If the battery is not dead, start checking the major connections.
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe