ETC Colorsource 20 Effects. How to turn off?

You do this with two cues, the 'lightning' and the 'following' cue that stops the effect.

Once you've recorded your Lightning cue (eg 3.0), stop the effect and record a second otherwise identical cue for the 'stop'
- I like to use a point cue for this, eg 3.1

Now give the first cue (3.0) a "Follow" time.

A Follow time tells the console to automatically run the next (following) cue (eg 3.1) some number of seconds after you press GO.

Adjust the Follow time so the lightning runs for the time you need - be that once, twice, one-and-a-bit etc.

Note:
To help with editing the initial 'lightning' cue, you can use Goto Cue or the Crossfader to fade into a cue without triggering the auto-follow.

You do this with two cues, the 'lightning' and the 'following' cue that stops the effect.

Once you've recorded your Lightning cue (eg 3.0), stop the effect and record a second otherwise identical cue for the 'stop'
- I like to use a point cue for this, eg 3.1

Now give the first cue (3.0) a "Follow" time.

A Follow time tells the console to automatically run the next (following) cue (eg 3.1) some number of seconds after you press GO.

Adjust the Follow time so the lightning runs for the time you need - be that once, twice, one-and-a-bit etc.

Note:
To help with editing the initial 'lightning' cue, you can use Goto Cue or the Crossfader to fade into a cue without triggering the auto-follow.