Hi, I have a 2011 C300 4Matic. Yesterday the antitheft mode was triggered and was going all night until this morning. The alarm would sound for a few seconds then stop automatically, and the hazard lights flashed continually starting at approximately noon. This happened until approximately 10 pm when the hazard lights stopped flashing. The car wasn't moved from its spot.

Today I found the key (that was the problem all along, I couldn't find the key!) and non of the buttons on the keyfob work, and the car itself doesn't respond to anything. No alarm sounds, no hazard lights, no response at all to the keyfob or the manual key in the ignition, no response to any buttons in the car (windows, lock/unlock on door).

Is this because the battery has drained, and I just need a jump?

When I do get the battery jumped, will I need to disable antitheft and if so, can I do that myself or do I need to take it to a dealer?

Thanks!