Need help with a flowering cherry tree

Hello! My daughter bought me a wonderful flowering tree for Mother's day from M&S. But then when it stopped flowering and leaves started growing some branches became dry. Other branches are still well and growing. I wanted to replant it in a larger pot and prune the dry branches but decided to wait and look for an advice. I wonder what i did wrong. Perhaps I overwatered it while it was in the house.
Unfortunately M&S didn't provide me with the name of the tree.
The first picture shows how happy it was when it started flowering in my house. The rest pictures show how unhappy it became now.
I would appreciate any advice if possible. Thank you in advance.

 

I hate shops that do this, its done for effect but not long term growing, almost like cut flowers, throw away once the show is over.

To me that is a hardy tree that was forced into flower just for the occasion, they couldn't give a stuff if the tree survives after that.

You on the other hand do, so good for you.

Personally I'd cut anything off that is obviously dead, then pot on into a pot slightly bigger, if you dont want to plant it into the garden.
Keep well watered and fed during the summer and resist the temptation to ever consider it to be a house plant in the future.

 

Thank you very much for your reply and advice. I also suspected that shops which are not garden centers sell plants which look good for the time of selling but such plants do not last long. The worst are cheap supermarkets like LIDL. I was tempted to buy 3 dwarf rhododendrons in buds but only one flowered after I bought them.Their leaves became dry in no time. I am trying to save them by repotting but I doubt that I'll succeed. It always upsets me a lot to watch how supermarkets treat plants. They should be fined for bad treatment of plants.

 

Pete this annoys me with shops and garden centres forcing plants in to flower well before their time just to sell them and show the plant at it's full beauty