How to hard reset Edge 840 to factory default?

The second option in the below:

www8.garmin.com/.../GUID-46A06A7C-1F46-4DBA-B010-DAD7BA6BE59E.html

Thank you for the link, but "This does not erase any of your data or settings. "
My question is about full reset to factory default, back to initial firmware version.

None of the reset options will change software version.

You can try this one. Power the unit off. Hold the lap an start buttons down. Power the unit on. Keep holding the lap and start buttons down for a few seconds and then releases them. That should perform a reset.

>>>Thank you for the link, but "This does not erase any of your data or settings. <<<

I think that would be the third option on that site.  You can connect the 840 to your computer and delete all files and folders  on the device.  Disconnect it and then do the third option.  That will get you back to a clean slate with the current software version.  You will need to reinstall the maps via Garmin Express.

Thank you!
I'm trying to solve my problem with WiFi\Bluetooth\Ant connectivity (after updating to 24.19 seems to be whole radiomodule stopped working).

I've tried 2 times, resetting was done twice. But unfortunately my issue was not solved - WiFi, Bluetooth and Ant are still not working on device.

Will try @looigi method with deleting all files and folders.

my new phone is not connecting to the device... the bluetooth is not being detected .. seems a bigger issue!