and <01> keep repeating on the 7 segment display. How can I avoid this?

This is error "E201." See the user's manual for possible causes and solutions.
Press the STOP key to clear the error. If you press the STOP key but the error doesn't clear, press the STOP key again. Up to 3 errors can be held. When the error clears, the unit number appears. (Normally "00.")