The difficulty shouldn't matter.
Did the Sparkmaster receive any air damage after you used the remote? That could include reflected damage if any of your characters have armour that reflects a portion of damage taken as air damage.
Using the remote to vent steam will create a cloud that can become electrified if the robot tries to use the ultrabolt attack, or the mages there try charging it.
There are also 3 levers in the cave you can use, rather than the remote.
