My 2005 c230 Kompressor got a new battery last month. I went to start it, and it was completely dead (phantom drain?). I hooked up jumpers to my truck, and the first time the interior lights came on and the key turned, but the engine didn't turn over. Now everything is dead regardless of jump. Did I screw up the electronics somehow? Is there a low voltage safeguard somewhere? fuse maybe? Thanks in advance for any help... P.S. I tried to use a jumpstarter batterypack, and it just continually beeped...like maybe there was a short.

 

Have you tested your battery voltage?