Ending, Restarting, and Debugging Sequences 
Select a sequence with the status Terminated. Choose Restart Selected Sequence.
You can also execute a restart for open sequences that have not yet been processed successfully. Every 5 minutes, the system automatically performs a retry three times one after the other.
Select a sequence with the status Terminated or Open. Choose Reject Selected Sequence.
Firstly, set an external breakpoint for the user who created the bgRFC unit that you wish to debug.
More information: Debugging bgRFC Units.
Select the unit in the bgRFC Monitor.
Choose Details.
Then start the appropriate sequence/message from the Sequence or Message Monitor. The bgRFC processes the unit automatically (processing may be staggered, depending on the volume to be processed), and the debugger appears.
Note
Follow the recommendations in SAP Note 1004248.