So I'm reading that your warranty DID in fact get voided because of the aftermarket tuner? From my knowledge even if it's erased it can still be seen. Nothing is ever completely erased, it just gets stuffed into crevices of the computer that most people don't know how to get to.
In a Windows computer yes, because deleting a file in Windows actually just renames it to something that the shell ignores and the data can sit there for years if that part of the drive is never reused. But this kind of extra space is not available in an ECM. It only has enough room for what it needs to hold (usual cost driven kind of thing), so when it is overwritten it is done so directly over the old data leaving virtually no chance for recovery. There may be theoretical options for recovering part of it in a lab...but that's way past what a dealer - or any computer shop - could even dream of pulling off.
I am however rather curious about why - apparently - the dealer didn't (/doesn't/cant?) have a copy of the OEM base tune available to reapply...in case of the odd emergency.
Scarlet Red 2010 Road Glide Custom named Trixie - She's a flashy little minx..
Basic black 1981 Tour Glide Classic named Alice - She's a sleeper project.