Marco: Do you remember where you put the Settings app in your app list? If so: press the OK button to open the app list, use the D-Pad to navigate and open the Settings app, then press D-Pad Right 3 times for Storage tab, press D-Pad Down once and OK to open USB Storage, press D-Pad Up once and OK to turn it on.
Contact entries can be exported within the Contacts app as well: in the main screen of the app, press D-Pad Down once to exit the search bar, press RSK for Options menu, D-Pad Down 6 times and OK for Settings, D-Pad Down 7 times and OK for Export contacts, OK once more to export to SD card, D-Pad Down once to exit search bar, LSK to select all contacts, and finally RSK to export (demostration video can be found
here on our Discord server).
If not, turn the phone on in
EDL mode and flash
Gerda Recovery. That way, you can use ADB in Recovery mode (
adb pull /storage/...) to pull data from the phone's internal storage. Note that in either ways, you will have to accept losing WhatsApp messages as they are end-to-end encrypted.
[the person with unbootable 2720 Flip 4G]: I believe you've messed up the partitions badly that the phone now falls back to
fastboot mode. You can restore the phone by using the EDL guide linked above to flash /boot and /system from a firmware backup.