I was just disabling dod on a 14 sierra E92 ecm, read stock file made my tune mod, licensed controller everything went great. I went to full flash and it started then gave me code$0677 Boot loader checksum failed.. ECM was dead no communication of any sort.. I got another ecm and put stock file from gm through j2534 and cranked up ran great.. I had suspected that the original ecm had been programmed with diablo but that wasnt confirmed only suspicion. Then I read out new stock file from gm and disabled AFM then had to purchase another license and attempted to reflash same results.... $0677 bootloader checksum failed. Now i have no communication with ecm getting error code $0101 No Data Recieved. Have I bricked 2 ecms?? I have tuned about 60 vehicles with EFI Live with no problems... I had good voltage when flashing everything off, lights a/c radio etc.. While i was waiting on ecm to arrive i tuned another truck with no problems... Any ideas?????