Problem when flashing Dys SN20A ESC

[phantom-8]

My Dys SN20A ESC has simonK bootloader and preflashed with blheli. I can flash them to SimonK with RapidFlash without any problem. However, once the ESC is flashed with SimonK, I can no longer flash it again with RapidFlash. It just reports "connection to the module failed". If I flashed the ESC back to blheli, I can flash with RapidFlash to SimonK. I also tested with kkmulticopter and it can flash the ESC even with SimonK firmware on it. Below are the summary of the test cases.

1. ESC has blheli firmware, RapidFlash works without problem.
2. ESC has simonK firmware, RapidFlash reports "connection to the module failed".
3. ESC has simonK firmware, kkmulitcopter works without problem.

Note: ESC has simonK bootloader and flashed via 1-wire servo plug with Arduino USB Linker.