On the picture below the connector is shown in the unlocked state. Release the touch pad cable and remove the palm rest assembly. There is an adapter between the DVD drive and motherboard. If you would like to replace the CMOS battery, simply unplug it from the motherboard and replace with a new one.
In order to unlock the connector simply lift up the right side of the locking clip with your finger nail. Slid the DVD drive to the right to disconnect it from the motherboard. In order to remove the wireless card, disconnect two antenna cable from the card, remove two screws securing the card and pull the card from the slot on the motherboard.
Once you have the remastered ISO, just burn it to a DVD with something like Brasero.
Or write it to your thumb drive (see, for example, How to create a bootable USB stick on Windows or How to create a bootable USB stick on Ubuntu).
Would you like to answer one of these unanswered questions instead?
Turn off the laptop, unplug AC adapter and remove battery.
I never did figure out why the UEFI/BIOS claimed the media was not bootable.