Check that your DOWN or LASER buttons are not stuck in place. Wiggle them on both control panels to make sure they have a little bit of give. If this is not the problem, wait for 10 seconds after turning the machine on without touching any buttons. If the machine makes a long beep with the FAIL light coming on, you may have a problem with your motor getting power. Check your motor cord for damage all along from the motor itself, through the back of the machine. If the covering of the cord is damaged, you can use electrical tape to protect it. If the cord itself is damaged, you will probably need an electrician to fix it. Contact support if you need a replacement wire.
If there is no beep after 10 seconds, turn your machine off and remove your front panel and detach the wires for the start/stop switch. Turn the machine back on. If you get one beep and a stitch, test all other switches (front and back). Turn machine off again, replace wires for start/stop and remove wires for single stitch switch. Turn machine on again and test all switches. You may have two blown switches. Once identified, replace non-working switches.