I would pull off the cover, like your doing a gimbal swap, and confirm the ribbon connector is solid, you shouldn't need to detach the gimbal itself. With the body color slotted cover off behind the gimbal, press the connector to be sure it's solid. You could try a power up with the cover off, and if it's still dead, pop the cable connector off, gently with a plastic pry tool. Then reconnect it. Watch a YouTube video on changing out the gimbal assembly beforehand. Good luck with it. If your still under warranty that gives you further options.