You can use the WaniKani Double-Check Userscript to override wrong answers. Be careful not to abuse it though. For most people, being unable to get an item right consistently due to “accidental mistakes” often means they don’t know it as well as they think they do. (Not saying this is necessarily true for you, but something to keep in mind…)
There is no way to force burns, but it would be possible in theory to make a script that automatically answers an item correctly every time it comes up without you having to see it. I don’t think anyone has written on which does this though.