Yes, unzip and place in the .kobo directory to upgrade or downgrade the firmware.
The only Kobo that had sticky tape and a physical seal was the Kobo Aura H2O. Since then Kobo has used a
HZO conformal coating to protect the electronics without having to physically seal the device.
The issue with opening it up is that there is some of the coating around the internal storage which makes it a pain to remove.