Dumb me. I connected 5V from my ftdi to LoPy's 3v3. I think it's fried.. Anything to try to bring it back to life?
@brotherdust Don't supply 3.3V to the 3.3V pin. This is an output only. It can burn up the power supply chip.
@brotherdust There is a slight chance that only the regulator chip died.
Try to supply with 3.6 V at Vin and take a reading at the V3.3 Pin.
a) If that is almost 0, then bypassing the regulator could be an option.
b) If you see 3.3V at that pin, the regulator is working (unlikely).
c) If you see something like 3.5V, the the regulator is shortened and the ESP32 and the other chips are most likely gone.
Still in cases b) and c) the device has a good internal supply and is in a working condition, and if it does not, ....
It's a pity that Pycom does not publish the schematics, so people must guess about a proper and failure behavior. This I cannot tell not much about FiPy, which has a separate power trail for the LTE chip.
@robert-hh Does this method actually work? I think I just blew up all my LoPy's and a FiPy. =(
@robert-hh Yes, GND was connected.
@jomifo just to be sure - did you connect GND too?
@jomifo Not good. Try to supply 3.3v at the 3.3v PIN
I see 5V at 3v3 pin
@jomifo Depends. Some posts in the forum tell, that this killed the regulator chip only. Then connecting to 5V would not do anything. When you do so, can you see 3.3V at the 3v3 Pin?
If yes, the ESP32 is most likely broken.
If not, you could try to remove the regulator chip and supply into the 3.3V pin with 3.3 V. The regulator is the smaller if the two chips next to the LED. It is really small, about 1.2 x 1.6 mm. If you heat it up on the top with an soldering iron hot enough, you can pick it up from the PCB. You have to clean the PCB surface then with desoldering braid. And yes, a 10x magnifying glass or microscope is helpful.