It's doesn't matter if the Dinan tune cause the issue or not; any dealer would strait up deny any drivetrain claim on sheer principle, just because of the Dinan tune is installed.
That's a 100% fact.
I'm not sure what exactly trigged the ultimate issue but I wouldn't exactly blame Dinan; it sounds like you lucked out and got a weak motor, the B58 can take a few more pounds of boost and survive, its headroom is practically endless, short of the fuel pump limitations.
Dinan would cover it, so hang in there until everything is worked out.
Engine warranty void by BMW, DINAN covers.
https://f80.bimmerpost.com/forums/sh....php?t=1614332