I have a GE switch working fine for years, I removed the faceplate and the pallet for painting, while removing the air plug, the light started blinking blue and remained that way.
No I reinstalled the whole thing and it’s still flashing and it does not work, manually or via the app.
It could have died. What model GE switch is it? There are quite a few of them nowadays. Some of the older ones (likely yours if it’s been working for years) have a reputation for failing.
Another possibility is that while removing the face plate you could have accidentally factory reset it and/or put it in pairing mode. Again, the model number will help determine this.
That model is the one known to fail. Unfortunately that is most likely what happened to yours.