What is not responding?
The CLI? Some Window?
Which files did you download? Did it compile correctly?
How do you open the file? which Program? Which version of it? Which OS?
Based on nothing but a weak "hunch", I would say you probably have a very large DB file, tried to do a long-running transaction, decided to kill it at some point, and now the roll-back journal is telling the engine to roll it back (automatic upon opening the connection) and trying an equally long-running process of rolling back the changes every time you try to open it (which cannot really take very long with most journal modes).
But without detail, it's extremely hard to say.