Hi,
At this point I would recommend you look at your java logs to see what is going on there.
/usr/sap/<SID>/DVEBMGS<InstNo>/j2ee/cluster/server0/log
Check your defaultTrace.*.trc log in detail
Check your applications.*.log log in detail
Go to subfolder /usr/sap/<SID>/DVEBMGS<InstNo>/j2ee/cluster/server0/log/system
In here is a security log if you say you can logon here and default trace is where I would check first.
server.*.log
security.*.log
Kind Regards,