E38 checksum $06FF now no data

[07 LBZ]

Please help, I was trying to turn off the AFM on a 2012 5.3 Silverado, I went to flash the truck, came up checksum $06FF so I tried a full flash, same result. Now when I try to flash the truck it comes up No Data and the truck will no longer start. Any help will be greatly appreciated so I can get this truck running again

[GMPX]

Try this tune instead, I'll explain what has happened if it works for you.
Just a calibration flash should sort it out (assuming that is all you were doing last time).

Cheers.