Did you remove the air bag recently?
I had the exact same problem on my friends 95 C280 when I was doing an evaporator job. From previous experience as long as you don't turn ignition "on" it should be OK, but for some reason this car turned on the SRS light. I'm not sure if it has something to do with timing (how long it's been disconnected). I had it disconnected over night. Anyway, it was doing the same thing like yours and I had a tech reset it.
I learned my lesson. From now on, I'll always disconnect ground from battery.