It most likely is motherboard damage, because you stated that the battery is fresh; if there's no sign of life, then it almost always indicates motherboard damage or zero charge in a battery.
Be EXTREMELY careful when servicing cameras; the capacitors inside are powerful enough to seriously injure or even kill. For DSLR cameras in particular, I would recommend sending the device back to an authorized service center for repair and using a spare camera in the mean time.
However, a replacement guide does not necessarily indicate that there are parts available from iFixit, especially in cases where the guide was written by the community and not by iFixit staff. iFixit does not offer replacement parts for this tablet, although you may be able to find parts on third-party marketplaces like Ebay or Amazon by searching the SKU on the part that you're looking to replace.
crwdns2934105:0crwdne2934105:0
crwdns2934113:0crwdne2934113:0
crwdns2915270:0crwdne2915270:0
crwdns2889612:0crwdne2889612:0
0