I have a Singer Confidence 7470.

here is a link for a free manual http://www.singerco.com/uploads/download/545_7470-instruction-book-engfrespa.pdf

Your manual ought to tell you or the Singer web site

Try a brand new needle. If the old one is bent, that could be why it is striking. If the new needle doesn't resolve the issue, the machine most likely has a timing issue. You can search for multiple web sites and videos for discussions and instructions for sewing machine timing issues. Or you can take it for service.

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the motherboard could be going out . it would be a good idea to have it checked

try changing the needle
make sure the bobbin is turned the correct way in the bobbin case
make sure the top thread has not come off the thread take up lever
if these suggestion don't help then the machine needs to be checked to see if it needs some type of adjustments

Look at page 80 of your manual.

There's a little finger on the left of the plate that fits in the corner.

Yes, try looking very closely at the needle assembly. Make sure the new needle is loaded with the flat side against the arm that holds it. If the machine is only a few months old, it's probably under warrantee. There should be a number to call on the serial plate. If all else, call the store you purchased it from. Sometimes they have sales people who are well versed with their equipment and can help you but I bet the needle is facing the wrong direction when you replaced it. Find any broken pieces of needle and remove them too. Look with a flashlight. I hope this helps!

It should be under warranty, take it to where you bought it, if after trying a different electrical outlet, and making sure that the cord is plugged in correctly, it still does not turn on, You could have a defective cord.

First, make sure you have the bobbin placed correctly in the bobbin case. There should be a diagram showing the correct placement and thread path. Your upper tension should be set at "3." Then be sure the needle is inserted correctly...the groove should be toward the front of the machine. And just to be sure, recheck the upper threading. Sometimes one missed little thread guide will cause the problem you're describing. I hope this helps and that you can get your machine running again!

The machine will feed the material you only need to guide it gently and it will sew the letters sideways.