Problem turning on unit with SD card

• Turn off the unit.
• Take a microSD card out of the slot. (Empty the microSD card slot.)
• Press and hold down the power button for a few seconds while pressing and holding down the "Home" (Silver Push Button) button. (Both "Power" and "Home" buttons must be pressed down until he see the phrase "upgrade system activated" in the middle of the screen.
• Release both buttons once the phrase "upgrade system activated" appears on the screen.
• Wait until it reboots. You will see the following sentences on the left top corner of the screen: Can not find any update image. Press MENU/KEY_VOLUMEUP key to init SD card, Press BACK/KEY_VOLUMEDOWN key to cancel.
• Press the "VOLUME UP" key. The volume up key is located at the left side of the unit and the button is closer to the built-in camera than the volume down button.
• Wait until it finishes making a partition and shut down the system automatically.
• Once the unit is turned off, your system will be reset to the factory settings. Thus, your previous data are lost at this point.

• Turn off the unit.
• Plug the unit into an electrical outlet.
• Take a microSD card out of the slot. (Empty the microSD card slot.)
• Press and hold down the power button for a few seconds while pressing and holding down the "Home" (Silver Push Button) button. (Both "Power" and "Home" buttons must be pressed down until he see the phrase "upgrade system activated" in the middle of the screen.
• Release both buttons once the phrase "upgrade system activated" appears on the screen.
• Wait until it reboots. You will see the following sentences on the left top corner of the screen: Can not find any update image. Press MENU/KEY_VOLUMEUP key to init SD card, Press BACK/KEY_VOLUMEDOWN key to cancel.
• Press the "VOLUME UP" key. The volume up key is located at the left side of the unit and the button is closer to the built-in camera than the volume down button.
• Wait until it finishes making a partition and shut down the system automatically.
• Once the unit is turned off, your system will be reset to the factory settings. Thus, your previous data are lost at this point.

To reset your TomTom device, do the following:

1. Check that the battery is charged properly.
   Charge your device for at least 2 hours before trying to turn it on again. Make sure the charging light on your device is on.
   
2. Remove the SD card
   If your device uses an SD card, remove it.
   
3. Reset your device.
   Use a straightened paper clip, or something similar, to push the reset button for at least 20 seconds. The reset button is a hole at the base/bottom of the device.
   
4. Turn your device on.
   Press the On/off button for at least 5 seconds or more, until the GPS starts up. It may take a minute or two of holding it down.
   
5. Insert the SD card
   If your device uses an SD card, insert the SD card.

My unit has the same issue, started a few weeks ago.

Here is a forum post where someone was able to fix their DXN7120 by replacing the button panel: http://www.kenwoodforums.com/viewtopic.php?f=11&t=1247

Here is a parts diagram showing the buttons (PN: X16-628):
http://www.pacparts.com/reference/880/DNX7120.pdf

Maybe someone could write up how to get the panel apart? Otherwise I will once I get the replacement part.

More then likely when the screen froze up on you it it had a little power glitch as well, nothing serious but it did wipe out some of the information in it's memory about the SD card.Power the unit up and let it come up with the error, then use the reset button. Might be hard to find since it's just a little hole with the word reset around it, using a paperclip push in the button and see what happens. If the error comes up again then i am thinking that you will need a new SD card. Quick test for this, remove the SD card from the gps unit and try rebooting, it should come up with an error, no SD card or no map, stick in an SD card from another device, 2gb, see if the gps can find the card, it should give you an error that says unable to find maps. If you get these error codes then most likely the gps unit is fine but it pooched your programs on the SD card.
Hope this helps

Make sure that you leave the unit plugged in for two hours, and remove the sd card, if you have a card in it.

On the top or bottom of the unit is a usb port and a reset button, take a paper clip and open it, then put the paper clip into the little
reset hole and push in for 30 seconds.

Turn on unit, hold the on button for 5 seconds, now turn off, now hit the reset button again as said above and then power on and run though
your menu and see if this did the trick, if not you might have to send the unit in for repair.

Please post back if you need any more help.

You will need to do a soft reset here are the instructions:

To reset your TomTom device, do the following:

1. Check that the battery is charged properly.
   Charge your device for at least 2 hours before trying to turn it on again. Make sure the charging light on your device is on.
   
   
2. Remove the SD card
   If your device uses an SD card, remove it.
   
   
3. Reset your device.
   Use a straightened paper clip, or something similar, to push the reset button for 15 seconds. See the pictures below for where to find the reset button.
   
   
4. Turn your device on.
   Press the On/off button for at least 5 seconds.
   
   
5. Insert the SD card
   If your device uses an SD card, insert the SD card.
   
   

Hi,
I had same trouble with my Lucca 3.4 and I resolved it.
1/ From "Lucca 3.4 GPS DVD" I copied all files from /Recovery  onto SD card

2/  With SD card inserted I started Lucca3.4 pushing 2 buttons (together)
  Switch ON/OFF and MENU, and he will reimage rom (took about 8min)

3/ when GPS auto-reboot-ed I pushed YES on screen and he started to upload
soft,files (took about 20min)

4/ after this I reinstalled maps from Lucca3.4 GPS DVD 

Now my Lucca 3.4 works fine again !
BR
Dan

To reset your TomTom device:
1. Charge your device.
Charge your device for at least 2 hours. Make sure the charging light on your device is on (except RIDER which has no charging light).

2. Remove the SD card.
If your device uses an SD card, remove it.
3. Reset your device.
Use a straightened paper clip, or something similar, to push the reset button. For a visual representation of the reset button, see below.
4. Turn your device on.
Press and hold the On/Off button for at least 4 full seconds.
5. Insert the SD card.
If your device uses an SD card, insert the SD card.

images of where to find the reset button can be found here.

It only goes down half way. You have to gently push it down the rest of the way to expose the SD card slot.