Hi vikas
If you cannot find the invoice in RBKP_Blocked table, and still your invoice document is shown as blocked in FI end, there is a table level inconsistency.
All the QM checks and other stuffs will only help you detect why your invoice is blocked. However, if it is not visible in MRBR or tables, you may need to contact SAP for clearing some table inconsistency that may have creapt in.
Alternatively, try reversing the invoice and post again
Regards
Vivek Singh