In the past, there is a high chance that your device can be fixed if there is something wrong with it but according to iFixit, the Samsung Galaxy S8 and Samsung Galaxy S8 Plus is as good as dead if you damage it.
iFixit dismantle the Samsung Galaxy S8 and the Samsung Galaxy S8 Plus to see if the device can be repaired if damage. The site ended up giving the S8 a 4 out of 10 repair score which means it is more repairable than the Samsung Galaxy S7 but still difficult to repair.
According to iFixit, they had to apply heat to the adhesive on the back glass panel although they did add that with the fingerprint sensor now in the back and that the new short cable connecting the reader to the motherboard made it less prone to accidental damage.
Like the Note 7, the battery of the S8 is also glued in which means you can just dismantle it and fit in a new battery pack.
If you damage your front panel, that is it. iFixit added that it is close to impossible to fix the front panel as you would most likely damage the other components.