If you don't have a memory card reader issue:
In Normal operation, you won't get any map view until the unit gets a GPS satellite lock.
You may have a faulty GPS antenna or connection-- or the antenna is blocked so it cannot "see" the satellites.
You can verify the card readers buy starting the unit up in Simulator, if they work you will get the mapping.
Humminbird Helix 12 CHIRP SI, 1198c SI, 1198c SI, ONIX 10 SI NT, Helix 7 CHIRP SI GPS G2, SOLIX 12 SI, 360, RC-1