Accidentally wiped *everything* - now stuck on samsung screen with lock topic

I have been using a custom rom via safestrap for a long time with no problem. Recently, I went to upgrade my rom and in safe strap, I foolishly did not back up. I did a factory wipe, but then I went into advanced wipe where I would normally check dalvik cache and a couple others, but this time I inadvertently checked ALL the boxes, including microsd card. So, I deleted EVERYTHING.

I took my external sd card out and put it in the computer, then copied my rom .zip file over to it. When I rebooted the phone though, I just get to the SAMSUNG screen with the little padlock on it and the word "custom" underneath. I can't seem to access safestrap to flash the rom over again.

What are my options?

Thanks!