All 4 tone lights (or ABCD lights on the FX100) flashing is 'recovery mode'. It is the intended behavior after a failed update. If you come across this mode, you must attempt to update the AMPLIFi again. Power down your AMPLIFi. When updating via PC, please connect the USB cable and make sure to boot the unit while holding Tone+Tap (amp, TT) or A+C (FX100) to put your AMPLIFi into Update Mode. Run the Line 6 Updater program found at www.Line6.com/software. For a guide, please r