Probably the map you uploaded is corrupt and therefore 'Loading Maps' in boot cannot complete. Read these threads: [Only registered and activated users can see links. ], [Only registered and activated users can see links. ] and importantly [Only registered and activated users can see links. ]. Post in the last one if you need help after thoroughly reading.
Next time you need to use a map of which you're not 100% sure, put it on an sd card rather than the unit. That way if it bricks you can simply remove the card and the boot can complete.
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