Updates stop if USB cable is removed

Question

I received the board and it worked great for about a week. Now the esp doesn't update the display anymore without being attached to USB. The battery is fully charged and I reflashed the board just to be sure. I tried to keep the board on USB over night which works, but the moment I remove it any updates stop.

Any idea what to test or change? Thanks for the great work and any help.

Update

I measured the voltage on the battery at 4V. It was plugged in and no burn marks are visible on the board. I also attached the serial output the board gives when plugged in (also then it is powered through the USB). 

Any other ideas what to look at? 

===========

log:
***********set register Start**********
***********set register  end**********
FS not formatted. Doing that now
FS formatted...
Loading config
Failed to open config file
State: 1
[SSID][pw]............
About to call OpenWeatherMap to fetch station's current data...
Getting url: http://api.openweathermap.org/data/2.5/weather?q=Durham,US&appid=some-api-key&units=metric&lang=en
[HTTP] GET...
[HTTP] GET... code: 200
start document
Getting url: http://api.openweathermap.org/data/2.5/forecast?q=Durham,US&appid=some-api-key&units=metric&lang=en
[HTTP] GET...
[HTTP] GET... code: 200
start document
Waiting for time
DST Rules Updated:
DST Start: Sun Mar 25 02:00:00 2018
DST End:   Sun Oct 28 02:00:00 2018
Min temp: 20.120001, max temp: 32.689999
Writing buffer
full init
***********set register Start**********
***********set register  end**********
Going to sleep

===================

Comments

A couple of questions...When you say the battery be fully charged is that because the device reports it as full or because you measured manually? Did you open the case to check whether the battery is still correctly plugged in? In case you opened it, did you notice anything suspicious like black dots on the PCB which would indicate a fried component? Could you please edit the question to include the output from the serial console (mask SSID/password).

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Do the lines "FS not formatted. Doing that now. FS formatted..." show up with every boot? If yes this is a sign that there is something wrong with the SPIFFS.  Can you tell us your settings in Arduino IDE > Tools Menu? I suspect that you might have set the wrong board or your FLASH settings are wrong. Make sure that you have:
- Tools > Flash Mode select "QIO"
- Tools > Flash Size select "2M (1M SPIFFS)"
The observed behavior might be explained by a setting of "512k (no SPIFFS)

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Lucas, what Dani described is documented at https://docs.thingpulse.com/guides/espaper-plus-kit/#select-flash-mode-and-flash-size However, the Arduino IDE has a handful of extra options we didn't document explicitly. Please let us know if you think the documentation is not sufficient - regardless of whether the root cause turns out to be the SPIFFS setting or not.

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Dear Marcel and squix78,

thanks for the help. I checked the arduino IDE setting and they look alright to me. flash size and QIO are set. I uploaded a screenshot to check if anything else might be off:

https://ibb.co/nkmVjJ

After flashing a fresh git clone with the wifi settings and openweathermap settings, I ran into another issue. After the first flash the board stopped reacting and  now refuses to sync. I connected it with the UART which was included and set the flash mode as described (hold S0 + press Reset) and run into (warning: espcomm_sync failed
error: espcomm_open failed
error: espcomm_upload_mem failed
error: espcomm_upload_mem failed
). The board power is on.

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I'm quite certain it's just an omission in your description, i.e. I don't doubt you executed it correctly, but "hold S0 + press Reset" should be followed by a "release Reset" (as per https://docs.thingpulse.com/guides/espaper-plus-kit/#put-espaper-into-programming-mode for anybody following along). Unfortunately those espcomm failures happen from time to time with Arduino IDE, caused by the underlaying esptool-ck flasher tool actually. I've seen this happen with any kind of ESP8266 module sporadically. Sometimes it takes a couple of attempts.

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I finally got the build to load with the correct SPIFFS setting, but end up with exactly the same result. The board is not powered by the battery but only by an external power source (either UART or micro usb)