Try a restart instead of a shutdown prior to trying to re-initialise a non-working hfa device.
diff --git a/driver-hashfast.c b/driver-hashfast.c
index 827d3a4..c91ea64 100644
--- a/driver-hashfast.c
+++ b/driver-hashfast.c
@@ -1337,7 +1337,7 @@ static bool hfa_running_reset(struct cgpu_info *hashfast, struct hashfast_info *
bool ret;
int i;
- ret = hfa_send_shutdown(hashfast);
+ ret = hfa_send_frame(hashfast, HF_USB_CMD(OP_WORK_RESTART), 0, (uint8_t *)NULL, 0);
if (!ret)
goto out;