Power On & Startup Sequence

Firmware Version


The firing module displays the firmware version of the device first, such as “5.0.2.” All devices synced together must use the same firmware version.

To learn more about firmware versions and how to upgrade your system, at no cost, please see Firmware Figured Out



tSt” displays as the firing module performs the following tests:

Cue responsiveness – Tests the responsiveness from each cue, ensuring each firing MOSFET turns on and off. If any cue is unresponsive, the system will display Er1 or Er2.

LED function – With the key in the TEST position only, the red and green LEDs will flash briefly.

Shorted/stuck button – During the self-test, if any button is pressed a false-positive to the shorted/stuck button test will occur, and error code Er3 will display.


For more information on 36M & 72M self-test error codes and how to resolve, see the Error Code Reference Guide.

Main Display


Used to display the module's battery life, address, bank & associated channel, and signal strength. For more information, see Viewing the 36M / 72M Main Display (link).

When the key is in the TEST position, the module will never arm or fire because of both hardware and software protection. We recommend TEST mode when checking continuity from the module locally.

When the key is in the ARM position, the module will arm and fire from the 18R2 to which it is synced. We only recommend arming the module when you are ready to fire your show.

When the 36M and 72M startup, the system displays the firmware version followed by a system self-test and finally the main display. The main display shows the system address, bank & channel, signal strength, and battery levels. For details on the 36M or 72M startup sequence, see the Startup-Sequence Reference Guide.

Was this article helpful?
3 out of 3 found this helpful

Articles in this section

See more
Our Support Team Hours:
9:00am - 5:00pm EDT Monday to Friday. We can be reached by phone at 518-741-4300 or email help@cobrafiringsystems.com
Emergency Shoot Site Support
COBRA offers a 24-hour support system for on-site emergencies. If you are on a shoot site and encounter a show-stopping issue, please reach out to us via phone at 929-930-6868.