Use an ; standard USB flashing tools (OCFlash) rarely work on v1.99 versions. If you'd like, I can help you:
While hex files are widely available, using them can be risky depending on your hardware. Version 1.99 is not an official release from the original developers; it is a modified version typically used with Chinese clone interfaces. Key Considerations for Firmware 1.99 opcom firmware 199 hex file work
: Connect the OP-COM to your PC. Install the FTDI drivers manually via Device Manager if they are not recognized. Use an ; standard USB flashing tools (OCFlash)