Hello Amit,
The link you have shared I believe would be a big change for you/your organization.
When did you assign it to your serial number profile ?
Did you create a fresh case post assignment ?
Can you create a dummy serial number to the vendor and take back with original serial number ?
You may consider raising the issue with SAP via SAP message (OSS), in case nothing is of help 
.
Do share the solution once you find it so it helps everyone.
Best Regards,
Ameya B.