"Firmware Upgrade Encountered an Issue" "Device not responding" Samsung Kies topic

I tried to flash an Android 5.0 ROM earlier, and my phone was only booting to the stock recovery (Safestrap was installed but I did a factory reset). Now, if the phone was turned off by removing the battery, it won't turn on when I hold the power button, or attempt to go into download/recovery mode. Nothing happens. If I plug it in, I can use whatever button combinations as normal. However, I don't think I can get to recovery mode. Both volume down/power and volume down/power/home enter download mode to the phone. I tried to flash a stock ROM in Odin, but it failed. Otherwise, it shows a screen that says " Firmware Upgrade encountered an issue. Please select recovery mode in kies and try again" And when I open kies, it just says "connecting" for an extremely long time until it eventually says "Device not responding" and I can't do anything. What do I have to do to fix this? I can't find anything for this phone that has had this problem or knows how to fix it. I've tried a few different things so far but flashing nothing in odin has worked. Any help is appreciated, thanks in advance.