The rescue method can be used to flash a bootloader (bu_[BOARD].opfw) file or firmware fw_[BOARD].opfw file.
For normal firmware update, the preferred method is the Automatic or Manual update described in this page: Firmware Tab
Click arrows left / right and follow instructions
The Uploader Gadget will detect your connected board and show the bootloader and firmware versions.
You can now load the desired bootloader or firmware file using the "Open" button
Pressing the button Flash will update the firmware on your board. A progress indicator shows the actual status of the firmware upgrade and identifies if the upload has been successful.
Once the firmware has been upgraded, one has to click Boot in the buttons area to start the program on the board
Firmware/Bootloader files have the file extension ".opfw" and are named typically.
The information area displays additional information about the loaded firmware.