My car is 2003 C240. I wanted to see how much oil I had in the engine using the trick to press the mileage-trip reset button 3 times fast. When I got the battery charge/oil level menu I switched to ESP Dynamometer menu and ran the test.

Now I get errors for ABS Not Active/Diag mode, ESP Not Active/Diag mode and BAS Not Active/Diag mode. The ABS light is on and I cannot turn the ESP on/off (yellow triangle with (!) Exclamation point).

What is this doing and is this bad to drive this way?? I want my ABS engaged again. I don't even know what BAS is!!

 

It sound like you have put the ESP/BAS/ABS systems into diagnostic mode. Have you tried doing the same procedure and resetting it? I haven't tried it myself.
By the way, BAS stands for Brake Assist System. In the event you have to slam on the brakes in anticipation of a crash, the BAS will take over braking and apply Maximum braking in an attempt to help you out. It engages the system when full braking is detected immediately after a sudden removal of your foot from the accelerator. Humans instinctively usually let up slightly on the brake after such a move so the car continues MAXIMUM braking as long as your foot is on the brake.