Smoke detectors will not reset after fire event or testing.
Smoke detectors latch on a smoke event. Power must be removed for a few seconds to reset the smoke detector. The Honeywell vista 20P will only reset zone 1 power and only if the fire initiating device is connected to zone 1. If you have 2-wire smokes connected to any zone other than 1, you will need to relocate to zone 1.
If you have a 4-wire smoke you will need to connect the power wires to the panel using pin 17 trigger (see below)
Even if you power the 4-wire smoke from zone 1 and connect the initiating wires to another zone, the fire event will not appear on zone 1 and the panel will not reset the power on zone 1.
You can power 4 wire smokes using the 12V aux + power and connect the ground to pin 17 on the board. Pin 17 can be programmed to stay high (creating a ground for the power) go low (open) when a fire event occurs on zone 1 you clear the panel (enter user code + 1, repeat if needed.
See *79 and *80 of the Vista 20P Installation and Programming Manual