[HP DesignJet T3500 series]

1. Use the power switch at the rear to turn off the printer, then disconnect the power cord. Reconnect the power cord, then turn on the printer.
2. Update the firmware.
3. Since the 79.2:04 system error is a generic error, the number of possible causes behind it is large. See Appendix A: How to troubleshoot system error 79:04 and 79.2:04 on page 143 in Service Manual.
4. Information available by pressing the red X icon while viewing the system error screen; or, preferably, provide the diagnostic package. See Appendix C: Obtaining the diagnostics package on page 156 in Service Manual.