I had my Mini (2011 N18 Turbo) out the other day and it went into some form of limp mode. It would not rev past 1000, I "limped" it back home about a mile. Checked it with a scanner and got a MAF sensor error. Cleaned the sensor and cleared the codes, now it won't start. It turns over and sounds like it wants to start but won't. It has fuel, spark and air. No additional codes from standard scanner. Borrowed a fancy computer scanner and got the following codes:

0x2DCF Valvetronic Sys: No Movement Identified
0x3427 Engine Oil Pressure Sensor Electrical: Short Circuit to ground
0xCDA4 PT CAN Message (Status Reverse Gear missing
0x2DCE Valvetronic Sys: No adjustment possible currently detected (Warning Lamp On)

Thanks Mike

 

Although it may not be related, take the valve cover off and check the timing chain.

Also i had same issue with my 09 MCS with MAF error. Despite replacing it twice i narrowed it down to engine harness.