I'm, a newby to my 2nd hand Dakota 20 and last night installed openstreetmap for the UK onto the sd card. All seemed ok when I tried basecamp. This morning tried to use it and it froze stating loading maps. 2hrs later still the same message. Connected it to pc but pc does not recognize it's there neither does Garmin. Have taken sd card and batteries out and it's still locked up but state..... 'loading waypoints, tracks and routes'. How do I fix it?