Fortigate D60 is dead after enabling SIP debug level 3

 Hi,

We have got Fortigate D60 (FortiOS 5.4) in one of our branch offices.

I configured SIP helper and wanted to troubleshoot some issue with SIP traffic flow, and use the following command to enable debugging for SIP:

diagnose sys sip debug-mask 3

When I issued this command I lost connection to Fortigate instantly and now it's not available neither via ssh nor via Web GUI.

Pings response time is about 15 seconds, so it seems like debug process eats all CPU resources of Fortigate.

This is remote office and I don't have physical access to the device.

Has anybody faced with such situation? Is this known bug in FortiOS? What can we do now to recover Fortigate?

Any ideas?

Thank you!