My DSO138 DIY Digital Oscilloscope Kit had a trouble in the firmware update. And it did not work anymore.
Even following these instructions it was not possible to revive the DSO138 DIY Kit ( http://www.jyetech.com/Products/LcdScope/DSO138_oscilloscope_upgrade.pdf )
Step 1: Solution
After several attempts to fix the problem, here was the solution: My step is to just download stm32flash (https://sourceforge.net/projects/stm32flash/) and using the command:
Stm32flash -w 113-13801-061.hex -v -g 0x0 COM3
COM 3 is my USB TTL converter.
Step 2: Tools
DSO to USB TTL connections:
GND to GND
TX to TX
RX to RX