I'm glad you're still able to flash new firmwares, because that "unable to program the requested memory region" message occuring when flashing a normal RGN (not a manually crafted one with weird region numbers) means that the flash chip is broken.
Some devices just don't automatically reboot after flashing firmware, GarminCure3 has nothing to do with that. So disconnect the device from the PC, turn it off, and connect it back.
Also if your device is able to boot with the corrupted internal filesystem, then you don't need patching firmwares with GarminCure3. Just format it with HMPRERPUSB.