I would probably start by unplugging everything from my QC including the expression pedal and the USB cable, nothing but the power supply (the factory provided one) and then restarting. If that didn’t work, and I had a recent backup. I would probably try the recovery procedure. You may have to select the full ‘Factory Reset’ option if the issue is that the QC is choking on a particular preset when it tries to start. Again though, backup required for this unless you want to start from a fresh QC.
Recovery Procedure: