@Maldonis
It may be that the device has a failing flash chip causing the bootlooping. If so then it's not recoverable by software means. While it's possible with the right kit and skills to do so, it's just not economically viable to replace and reprogram the chip.

However, it's also possible that the dezl 580 is one of the Garmin devices with cannot boot if the file system is completely empty. While most can boot empty (but of course not navigate or even show a map), some devices require at the very least an empty Garmin folder created in the root of the internal memory before they can completely boot, and some others require actual files onboard. Read about that in initial post in Kunix's Cure3 thread: [Only registered and activated users can see links. ]. Just be sure you don't copy from a recent backup any files that may have caused it to bootloop initially.