Hi Carlos,
As Benjamin has mentioned there are various logs that you can review. The obvious ones would be in the stdout and stderror logs.
Please see the link, which references the JVM Logs interpretation https://www.ibm.com/docs/en/was/9.0.5?topic=logs-jvm-log-interpretation.
This has additional links at the bottom, which navigates you how to view the JVM logs from either the IBM WAS Admin console or in the Windows explorer profile directory. As well as options for changing the JVM log configuration to provide more / less detail. Normally changing these settings require an IBM WAS restart.
Can I assume that when deploying the application that while it installs successfully, there are warnings when it's installing?
Does your application using any JNDI lookups, where the driver is not configured?
Does your application use security groups on the deployed application?
Does your application use AD security?
I realise there is likely more questions than answers however, I'm just trying to understand what components are involved if the log doesn't show signs of an obvious error.
Hope this helps.