I'm having the same problem with a new 3.4d install. I ran into the pdfbox error that killed the process. I replace pdfbox with a newer version, deleted the catalina.pid file and attempted to restart. mysql starts and tomcat says it's restarting, but something interrupts it or shuts it down.
service alfresco status says tomcat is not running but mysql is. A new catalina.pid file is created, but when I try "service alfresco stop" I get the "found but no matching process was found" error. Which log file do I look in to find what's interrupting the tomcat startup?