Might be. If possible, can you open that expansion board and check if there is any visible damage? If you are not sure, take a high resolution picture under good lighting conditions and post it here (or send to [email protected]). It station 24 triac is damaged, it can be fairly easily replaced.
In addition to # 24 not working # 22 is also stopped working.This is the second expansion board of three. #6 and #8 as marked on the board have visible damage.The black rectangles look melted.I have very little experience soldering.The board is markedv1.1 07/2013.Are all the boards made the same by the same manufacturer?Is the new 16 zone built better?How often can this be expected.This open sprinkler is now my only controller running my nursery in a desert climate.
One thing you should check is if station 22 and 24 solenoids are shorted. To do so you can measure the resistance between the COM wire and station #22 (same with #24). The typical coil resistance should be around 30 ohm. If it’s too low (like below 15 ohm), you should consider replacing the solenoid. OpenSprinkler doesn’t have shorted solenoid detection feature yet. In the case of shorted solenoid, the fuse is supposed to blow, but if the fuse doesn’t kick in quickly enough, it might damage the triac. Another possibility is damage due to high transient voltage.
If you don’t need #22 and #24, you can use a diagonal cutter to carefully clip away the damaged triac. If you do need #22 and #24, send an email to [email protected] so we can arrange for support.