DRK= Device root key
DMVT=dm-verity verification failed
DRK is a device-unique asymmetric key pair that is signed by Samsung’s root key through an X.509 certificate. This certificate proves that the DRK was produced by Samsung. The DRK is generated at manufacture time in the Samsung factory and is stored on the device encrypted by the DUHK, thus binding it to the device.
This Happen with Rooted Device,like S6/S6 Edge, S6 Edge plus, Note 5, S7/S7 Edge etc...Afetr flash rooted Device it will stuck on start up with "dm-verity Verification failed"...need to check DRK first...