I am playing Lego Harry Potter year 5 I am stuck on a trip to hogsmeade on ipod

I am stuck in the room after you gather all the students I did everything you can do in there other then get the chest behind the boars/pigs head I have tried reducto and all the other spells have tried using different people. Has anyone had this problem? I can't seem to get the chest open and I need the gold wizard hat thats in it to complete the entire level. If anyone has any ideas or has had or is having the same problems please let me know. I was wondering if anyone has figured out how to get it? I already killed the dementor that is right there so all I need to know is how to get into this stupid chest.. Have tried the last couple days and even bought bellatrix because I thought it initially may help.

I know that this is a year after you asked, but here it is:

Harry (specifically) has to watch the video of the Basilisk's defeat that is inside the painting next to the barrels.

Not sure if this posted, so trying again with more detail--

I'm assuming that if you've done everything else, then you've already moved the barrels in the corner, cast reducto at them, and built/ hung the painting.
Change the character to Harry, go over to the painting by the barrels, and watch the video of Harry defeating the Basilisk in year 2. That will give you the blue square in the floor to leave.

can't get all the charachaters on hogsmeade