If you do want to proceed, check or garmin.openstreetmap.nl — but backup your original firmware first.
You tried a hack, and now your screen is stuck on the Garmin logo, or it won't turn on at all. Don't throw it away. garmin nuvi hacks
Many nüvi models have a "secret" menu used by technicians for troubleshooting. If you do want to proceed, check or garmin