HELP URGENT!! 2014 silverado e92 checksum failure/no start

[RedlinePerformance]

I have a customer that I was flashing in a modified tune into his e92. goes through all the progress bar then throws a checksum failure In the last 3 seconds, truck is a 2014 Silverado 1500 5.3. he has to leave for work Friday morning in this truck so please help. I have the October 28th software and updated firmware. this is the stock file attached

[GMPX]

Was it previously tuned by Diablo or LS2Edit by chance? I'll get your file fixed up shortly.

[RedlinePerformance]

no, completely stock

[GMPX]

I'm seeing evidence of that not being the case, doesn't matter. Please see if this file will flash in ok.

Cheers,
Ross

[RedlinePerformance]

im flashing it right now. thanks for helping. I can assure he has never done anything but it is a conversion truck with lift and bigger tires so maybe they go in and change some stuff at the dealer or conversion place

[GMPX]

Is it up and running again?

[RedlinePerformance]

FIXED IT!! thanks so much. what was the problem in the file?

[GMPX]

It is no so much a problem with the file as such, a number of aftermarket tuners (trust me, this wasn't 100% GM factory fresh) modify some data so the CVN's remain standard, the CVN is how the dealer can tell if the car has been tuned. Unfortunately with the safety checks we have in our reflash routines it gets confused and thinks the tune didn't get flashed correctly. We are obviously going to have to fix this so any previous tunes from other software will be usable.