Older software for the Edge 500 can cause the device to either lock-up or get stuck in a constant power cycle, resulting in the device to never progress past the startup screen. This can be caused by a corrupt file. The device must be held in mass storage mode to access and delete the NewFiles folder.
To delete the NewFiles folder:
The device will now proceed past the startup screen. You will need to update to the latest software version using Garmin Express.
Garmin Express - https://connect.garmin.com/en-US/start