Container with a different texture/model when opened

Hello, I've been trying to make a custom chest like item that when opened had a different texture to show its open, I'm currently using another model for this and a procedure to replace it and put the original back when closed, thing is it erases the contents when I do this, probably because I've just replaced it with a blank version.
So any help on figuring out how to copy all the NBT stuff into this new one is appreciated, I'm not too good at the blockstate stuff yet! :)

Also if it requires me to do a little coding I'm up to give it a go.