ML320 3.2Litres V6 Gasoline 2002

My ML320 broke down and wont start. Apparently an injector hasnt been working properly and it has created more problems in the engine. At the garage they tried first the battery and it wasnt the problem after that they tried the starter and they said it wasnt the problem after that they tried to move the camshaft manually and they couldnt. They said this is a bad thing because it didnt move clockwise though a little anticlockways.
I asked for the scaner but the mechanic said as its impossible to start the engine its impossible to use the scanner.
Please i need advice; i cant pay the official mercedes garage; at least i want to have an idea what should i be facing.
Looking forward for your advice asap.