Latest Jyetech update version 113-13801-066 for DSO-138. This version fixes triggering at 50ms and below, trigger LED, and removed fake product warning.
Forum thread: https://forum.jyetech.com/viewtopic.php?f=18&t=1101
Flash instructions via UART pins (requires soldering/desoldering JP1 and JP2 jumpers): https://jyetech.com/wp-content/uploads/2018/07/dso138-firmware-upgrade.pdf
Alternate flashing using SWD pins via ST Link type adapter:
Install drivers and STM32 Link Utility (you may need to reboot after for the adapter to be visible)
- Connect ST Link adapter to SWD pins
- Connect ST Link software to DSO-138 (Target>Connect in menu)
- Open hex file File>Open
- Select Target>Program & Verify