Hi Hari,
From the error message it looks to be kernel problem
Kernel incompatible to already connected instances
Can you follow the steps below to ensure whether db is running fine
1) Stop sap applicaiton using stopsap r3
2) Stop database using db2stop
3) start database using db2start
4) Check connection with database using R3trans -d. If return code is not 0000 then share the trans.log details.
Regards,
Deepak Kori