Did you have your Argon updated to 0.8.0-rc.27 before flashing the new application.
If not, your new application is probably targeted at rc.27 and now Safe Mode Healer is trying to update your system in order to make it compatible with the application you want to run.
Normally that will take a few minutes and some reset cycles. But since you have already interrupted that self-healing process it can be that it won't get out of that by itself anymore.
Just let the Argon sit in Safe Mode for at least 10 minutes. If it won't come back after that you can try to update manually by following these steps
After that put your device in Listening Mode (blinking blue) and post the output of particle serial inspect