Hello
Check if Db connection is Ok
brconnect -u / -c -f check > D:\BR.log 2>&1 & notepad D:\BR.log
R3trans -d -v -w D:\R3tr.log 2>&1 & notepad D:\R3tr.log
If possible Stop SAP & then DB, clean IPC shared mem (cleanipc <InstanceNumber>) and restart DB & SAP.
Regards