bricked ESP8266 ? any command errors with "Failed to write to target RAM (result was 0107)"

I got the same problem:

root@raspberry:/home/pi/espurna# stty</dev/serial0
speed 38400 baud; line = 0;
min = 1; time = 0;
-brkint -icrnl -imaxbel
-opost
-isig -icanon -iexten -echo -echoe -echok -echoctl -echoke

root@raspberry:/home/pi/espurna# time ./esptool.py -p /dev/serial0 write_flash 0x1000 espurna-1.13.2-itead-sonoff-th.bin
Serial port /dev/serial0
Connecting....
Detecting chip type... ESP8266
Chip is ESP8266EX
Features: WiFi
MAC: dc:4f:22:41:9c:58
Uploading stub...

A fatal error occurred: Failed to write to target RAM (result was 0107)

real 0m2,423s
user 0m0,412s
sys 0m0,057s

I am using Raspberry Pi GPIO TXD0, RXD0 and GND. Sonoff is powered by its own power supply (240VAC, I am a professional electrician).

Any quesses what can cause this ?