Op GPSrChive staat een Foreced USB mass storage mode die net wat anders begint dan die methode die JaVaWa beschrijft.
Wellicht te proberen.Zie:
https://www.gpsrchive.com/Oregon%207x0/index.htm bij Troubleshooting.
Forced USB Mass Storage Mode
The following procedure forces your Oregon 7x0 into USB Mass Storage Mode so that you can delete/remove/rename any recently added files:
1.Remove battery and µSD card from your Oregon 7x0
2.Connect the Oregon 7x0 to your computer with a USB cable
3. As the Oregon 7x0 powers up and begins the boot process, immediately press and hold the power button without disconnecting the USB cable until the Oregon 7x0 powers down
4. Press and Hold the power button for 30 seconds, or until the USB symbol appears on the Oregon 7x0 display
5. The Oregon 7x0 will be in USB Mass Storage Mode
6.Remove or rename any recently added maps, images, gpx or other files that may be causing the issue
7. Disconnect the Oregon 7x0 from the USB cable
8. Install previously removed battery / µSD card and power up the Oregon 7x0
Repeat Steps 1-8 as needed until the Oregon 7x0 boots properly