Well, I really don't know. The guy from the plant left a message and he didn't say if he already tried to reboot the PLC, or what are the leds displaying. He only asked if he could clear the fault without needing someone to go with a PC and RSLogix 500.
Since I am a novice and I didn't want to appear as clueless as I am when I call him back, I decided to check with the old folks here what can be done in this case.
A related question: can the programming hand-held programming devices clear the faults?