Help with hidden button

Could someone please help me with this button in the Abandoned dungeon?

https://imgur.com/LlWbdx5

I been tried for 4 days, read forum but can't find it myself :( I fall into despair :D

Thanks!

That door is not opened by a button, it's opened by clearing the dungeon.

many thanks, I'll try)

OOps, do not know why I became anonymous :D many thanks one more time :)

can someone help me one more time? ;D

I pressed the button in the Dark dungeon in the library room above the table between 2 round windows, and nothing happened. There are only 3-4 short corridors and 3 closed doors - 2 grates and one door. Cannot find another button. if you remember this location, so could you please tell me what do i have to do?

https://imgur.com/CaZGNlT

can someone help me one more time? ;D

I pressed the button in the Dark dungeon in the library room above the table between 2 round windows, and nothing happened. There are only 3-4 short corridors and 3 closed doors - 2 grates and one door. Cannot find another button. if you remember this location, so could you please tell me what do i have to do?

https://imgur.com/CaZGNlT

There is another one right below the window near the table, on the wall. 

There is another one right below the window near the table, on the wall. 

:D many thanks, I just opened my own scrren shot and seen it at the same moment))