ESP32 interacts with app via Bluetooth and is being deployed at a location where I cannot get access to for any diagnosis. if I have to switch off esp32 interacting with app . how can I do it ? what are tools that can be used to establish such task?
what I am able to understand is I need a solid backend to establish such task. if so how can I start working on it on MIT app inventor platform.
Dear @Vrt ,
what do you mean with "switch off" ? Do you really want to remove the power to the ESP ?
If so, it is quite easy: you can use a relay, driven by an output pin of the ESP32 itself, that cuts off the 3.3 VDC to he board, but how can you switch it on again ? You can do it by means of a momentary pushbutton, that overrides the relay, but you need to have access at that pushbutton, even if you cannot have access to the ESP32 board.
Or, much simpler, tre power supply to the ESP32 is given by a power supply that you can access (though the ESP32 itself is unreachable).
EDIT of course in the first case the app, via BT, sends a message to the ESP to say "please switch yourself off" 
Maybe it would be easier to ask the ESP32 to switch off whatever it was controlling?