Starting EBS Fails with Exception while starting server oacore_server1 Unable to obtain lock on oacore_server1.lok

startup weblogic fails with:
Starting server oacore_server1 ...
Error Starting server oacore_server1: weblogic.nodemanager.NMException: Exception while starting server 'oacore_server1'
ERROR: Unable to start up the managed server oacore_server1
07/06/14-13:37:05 :: admanagedsrvctl.sh: exiting with status 1
The oacore_server1.out log file under $EBS_DOMAIN_DOMAIN\servers\oacore_server1\logs\ shows:
<Jul 6, 2014 1:33:46 PM EDT> <Info> <WebLogicServer> <BEA-000377> <Starting WebLogic Server with Java HotSpot(TM) 64-Bit Server VM Version 23.25-b01 from Oracle Corporation>
<Jul 6, 2014 1:37:04 PM EDT> <Critical> <WebLogicServer> <BEA-000362> <Server failed. Reason:
There are 1 nested errors:
weblogic.management.ManagementException: Unable to obtain lock on ..EBS_domain/servers/oacore_server1/tmp/oacore_server1.lok. Server may already be running
    at weblogic.management.internal.ServerLocks.getServerLock(ServerLocks.java:206)
    at weblogic.management.internal.ServerLocks.getServerLock(ServerLocks.java:67)
    at weblogic.management.internal.DomainDirectoryService.start(DomainDirectoryService.java:74)
    at weblogic.t3.srvr.ServerServicesManager.startService(ServerServicesManager.java:461)
    at weblogic.t3.srvr.ServerServicesManager.startInStandbyState(ServerServicesManager.java:166)
    at weblogic.t3.srvr.T3Srvr.initializeStandby(T3Srvr.java:881)
    at weblogic.t3.srvr.T3Srvr.startup(T3Srvr.java:568)
    at weblogic.t3.srvr.T3Srvr.run(T3Srvr.java:469)
    at weblogic.Server.main(Server.java:71)
The previous shutdown was not clean and the .lok file from the previous startup was still there.
SOLUTION
1. Remove or rename the file: $EBS_DOMAIN_HOME/servers/oacore_server1/tmp/oacore_server1.lok.
2. Re-teststarting EBS again.