Hey Guys i'm From Aus Love the project.
Been using Blynk for my garage door but with extra coding for feedback loop hated it found you guys.
Anyway i am using NodeMCU its a ESP8266 with built in FTDI and voltage step down great product.(find info here https://nodemcu.readthedocs.io/en/dev/)
I could flash fine then put in to config mode and upload SSID,Pass,server... i can see it on the network even, then after restarting the Blue led just flashes slower than when in config mode and it wont even go back into config mode so i can see status.
For some reasons ESP lose estabilished connection with your wifi network. when it happen Supla software perfofm ESP restart so you don't have enought time to hold the button pressed. Turn off your WiFi network for a moment and then press the button.