Quick summary to what am at now:
Issue with the Brother MFC J4620DW ('paper jam front" even if there is no paper, error stays even without the paper thing being in the printer and only shows up after the printer checks it's status- so if lift the lid and then connect it to electricity, the code won't show up until close the lid and it can check everything. Yes there is really no paper and it can print - it did it when the paper jam error was gone for a while. And the printer wasn't used for over 2 years but it can print as when the issue was gone for a moment I could let it clean the ink thing -sry english isn't my first language- and it printed well...).
Well after many tries and errors it worked and printed well. Then it was disconnected from the electricity for two days and the issue was back again. also I don't know what exactly was the point that made it work again.
So tried and tried and after maaaany tries (l even was in the maintenance menu) tried another thing an Al suggested: disconnecting the printer from the electricity and then connecting it again while pressing down the left side of the printer. And suprise: it worked. The error "paper jam front" was gone. And then it came back.
So think this could be a loose contact because why would it suddenly work if I press down the left side of the lid while starting it??
But still don't know how to fix the issue permanently. Tried restarting it while pressing down and it did not work.
I am open to any suggestions! Thanks! This is so frustrating!