After sitting for a bit, I planned to take my MB out for a Halloween drive. The day before I drove it to the gas station and it started with no complaints other then my siren sounded weak, so I put it back on my 4A charger maintainer. That day, it started up with no problem, drove it a little ways, started it again and drove home. When I tried to start it again, I had no electrical. No headlights, siren, or starter. When I pressed the starter button I noticed my gauges slowly dying, but would return to their position when I took my foot off. Any ideas here?