Hi everyone, i am new here but have insight into this issue. Hopefully by now you have resolved this. i myself went into full panic mode last night when i finally got everything hooked up and my arm wouldn't go up and down either. Just In case you still need help, or for anyone reading this in the future i found some info that could help, but didn't find it on this forum, so here is what i learned. Luckily for me, the fix is super EASY and fast, one flat head screwdriver could solve your issues.
First if you didnt know, the carriage holding the blade if pushed down toward the vinyl, should spring back up by itself, if it doesn't, try this. Remove the carriage housing by pushing down on the two tabs on top of the carriage box, and leaning it away from the machine. you will see a solenoid, and here is a link to a video that will show you what might be the issue, apparently its fairly common.
Laserpoint II repair
This fixed my machine and it works great now only difference for me was mine was stuck from the opposite side as the video, quick pry on the left side and the arm popped right up.