No electrical anywhere

Lot of detail here. Replaced plugs, all was good. Left sit for few days, started, ran real rough, gray exhaust smoke, engine misses. Ran down the road it smoothed out. Left sit 2 days, drove to town ok, except it sounded "loud". Something abnormal. Left restraurant, engine started, DTL running lights only outside (I think, did not get out to check), all accessories dead, driver door switch paned backlit only. No locks, no windows. Turned car off to try resetting computer (?). Will not crank. DTL's and hazard light only. Everything else dead. Sent to repair. At some point in their diagnosis of ignition and such, trouble went away. Cannot replicate at this time. Any ideas? Repair shop said it could not be something I did under the hood.