This is a fun little puzzler!  The concept of staying powered up is simple but is used in such interesting ways.  The fact that the wire acts as a physics object was such a fun surprise.  The boxes themselves become an interesting challenge in later levels.  This has a surprising amount of polish for a game jam game.  I'd have liked to see a better indication of attaching/detaching from the cord and auto-detaching between levels (that was a bit confusing).  But overall, great work.