ESP8266 NodeMCU MicroPython garbage in serial, cannot erase_flash or upload files

Question

Looks like I broke my NodeMCU Lolin esp8266 module, please confirm)

Firstly everything worked fine, but then...

1. I uploaded a bit strange boot.py to play with UART0

#boot.py
import uos, machine
import gc
gc.collect()
import esp
import time
esp.osdebug(None)
uart = machine.UART(0, 115200)
def uart_test():
 print('before disabling REPL on UART')
 uos.dupterm(None, 1) # disable REPL on UART(0)
 print('after detaching REPL')
 time.sleep(5)
 uart.write('123')
 r=uart.read()
 # reattach REPL
 uos.dupterm(uart, 1)
 print('after attaching REPL')
 print('r: ')
 print(r)

2. Then I uploaded main.py with blink in infinity loop with time.sleep() to check state while I mount module in box.

#main.py
import time
from machine import Pin, Signal
led = Signal(2, mode=Pin.OUT, invert=True)
while True:
 led.on()
 time.sleep(1)
 led.off()
 time.sleep(1)

3. Then, when I was mounting module in box I accidentally tore one element from PCB, but then solder it back. I don't know what is this element and what purpose of it. I marked this element on image IMG: broken element

And after all of that I cannot connect to module by serial port, I see only garbage in screen, tried different baud rates. IMG: screen is empty and doesen't react to keys or Ctrl+C

After resetting board only garbage in screen IMG: garbage after reset

Also I cannot erase flash using esptool.

MCU is working because when it powered led is blinking as it programmed in main.py

I tried to enable bootloader mode by connecting GPIO0 with GND, blink is not working in this mode, but esptool.py also doesn't work in this mode. esptool log

python3 -m esptool --port /dev/cu.usbserial-142240 --baud 9600 erase_flash
esptool.py v3.1
Serial port /dev/cu.usbserial-142240
Connecting........_____....._____....._____....._____....._____....._____....._____
A fatal error occurred: Failed to connect to Espressif device: Timed out waiting for packet header

esptool log with --trace arg

python3 -m esptool --port /dev/cu.usbserial-142240 --baud 115200 --trace erase_flash
esptool.py v3.1
Serial port /dev/cu.usbserial-142240
Connecting...TRACE +0.000 command op=0x08 data len=36 wait_response=1 timeout=0.100 data=
 0707122055555555 5555555555555555 | ... UUUUUUUUUUUU
 5555555555555555 5555555555555555 | UUUUUUUUUUUUUUUU
 55555555 | UUUU
TRACE +0.000 Write 46 bytes: 
 c000082400000000 0007071220555555 | ...$........ UUU
 5555555555555555 5555555555555555 | UUUUUUUUUUUUUUUU
 5555555555555555 5555555555c0 | UUUUUUUUUUUUU.
TRACE +0.023 Read 1 bytes: e2
TRACE +0.000 Read invalid data: e2
TRACE +0.000 Remaining data in serial buffer: 
 6efe6ee43cfe2792 07eceeee708ef21c | n.n.<.'.....p...
 1e0e1c906e6c6c1c 9227c71eeee76c | ....nll..'....l
.TRACE +0.056 command op=0x08 data len=36 wait_response=1 timeout=0.100 data=
 0707122055555555 5555555555555555 | ... UUUUUUUUUUUU
 5555555555555555 5555555555555555 | UUUUUUUUUUUUUUUU
 55555555 | UUUU
TRACE +0.000 Write 46 bytes: 
 c000082400000000 0007071220555555 | ...$........ UUU
 5555555555555555 5555555555555555 | UUUUUUUUUUUUUUUU
 5555555555555555 5555555555c0 | UUUUUUUUUUUUU.
TRACE +0.002 Read 1 bytes: ee
TRACE +0.000 Read invalid data: ee
TRACE +0.000 Remaining data in serial buffer: 
 240eec6e9c9c8c9c e70e026c6ce4ee9c | $..n.......ll...
 6e6e00f26c62e4ee 70e26ee2ec626c | nn..lb..p.n..bl
...
# and a lot of similar messages

What is with my nodemcu module is it died or not? What can I try to do?

Answer 1

It's more likely that you are experiencing hardware related issues than software related issues as you imply yourself.

Re-solder the part that broke off and try again. You probably broke of a resistor/capacitor that is used for noise filtering the output (I am not a hardware guy) or something that is vital to regulating the voltage required for the board to operate.

EDIT

As indicated by: https://raw.githubusercontent.com/hallard/NodeMCU-Gateway/master/pictures/NodeMCU-Lora-Gateway-top.png it seems, albeit that board is of a different design, that you broke off a capacitor or diode. Either resolder or get yourself a new one (100nf) or a diode (1N4148)

• Philipp: I tried it several times, there is no effect. I think thai I burned some elements in CH304 serial to usb converter circuit. And it's cause why it's not working. I have external usb to uart converter, maybe I'll try to connect through it, or buy new one nodemcu. Anyway, thanks for advise!
• Philipp: I figured out that it's diode on the PCB board, I soldered it out and similar neighbour diode. Checked it by multimeter in diode test mode and both works proper. Then soldered it back, but it doesn't helped.

Answer 2

Conclusion:

Today I received USB to UART converter, connected it to TX and RX of my ESP8266 board and everything works well. So the problem is with onboard CH340 converter.