Forget about that muck in the top left corner of the plastic tank as every Bosch dishwasher has a build up of muck in that corner. Its not a blockage its just muck on the plastic chamber itself not blocked in there.
Im taking it you have checked the drain hose and were it drains out to. If it goes under the sink then remove the spigot it pushes onto and make sure that's all clear in there.
Then get a bowl and hang the hose in there and then start a cycle as the first thing it does is pumps the water out. When it does this give the drain hose a good hard shake and see if any muck or fat comes out of there.
If its still blocked then look at the plastic tank and at the bottom you see the 2 hoses.
Pull the hose off on the end left. It will just pull out so pull out and blow hard through it and make sure its clear. If its not then the blockage is in there.
If that all clear then you need to remove the other hose as well and remove the plastic chamber off the side.
Now you need to reach round under the dishwasher to the other end of that hose which goes to the sump and remove it.
From there clear out any blockage in there and see how it goes.
As if its not draining and the pump is new then its either blocked inside the drain hose or the sink spigot or the other hose going from the sump to that plastic chamber.
Check them out and see what you find and let me know how it goes.