When does the flip of a hit icon to a critical icon happen? My interpretation is that the flip happens during the attacker's modify attack dice step after the defender's modify attack dice step. Am I wrong?

When does the flip of a hit icon to a critical icon happen? My interpretation is that the flip happens during the attacker's modify attack dice step after the defender's modify attack dice step. Am I wrong?

You're not wrong. Sensor Jammer happens during "Defender Modifies Attack Dice", before the Mangler Cannon's effect, which happens in "Attacker Modifies Attack Dice". Of course, if the attacker has a focus, they can turn the eye back into a boom and then Mangle that boom into a kaboom.

As noted the Defense gets to modify the attack first which is before the Attacker gets to modify using the Mangler ability.

I may be wrong but the only thing that would change dice before either side gets to make any modifications is the HLC.