Since DSM does not allow downgrading if you choose to preserve settings, you need to trick it to believe the installed version is older version
Assumption:
You have updated to newer version 6.2.2 (DSM_DS3615xs_24922.pat) and it is bricked
You want to rollback to 6.2 (DSM_DS3615xs_23739.pat) with setting preserved
Prerequisite
Your original USB boot key (For 3615) (USB Drive A)
Any Live Linux USB key (e.g. Debian) (USB Drive B)
An additional USB b
Since DSM does not allow downgrading if you choose to preserve settings, you need to trick it to believe the installed version is older version
Assumption:
You have updated to newer version 6.2.2 (DSM_DS3615xs_24922.pat) and it is bricked
You want to rollback to 6.2 (DSM_DS3615xs_23739.pat) with setting preserved
Prerequisite
Your original USB boot key (For 3615) (USB Drive A)
Any Live Linux USB key (e.g. Debian) (USB Drive B)
An additional USB b