One beep means the MPEM is not reading the lanyard.
Would make sure it is the correct lanyard. Clean the lanyard with soap and water.
If that doesn't work you will probably have to get the lanyard reprogrammed.
I bought the candoopro and I know the key is programmed. It's a brand new key. When I put key on and push start I get one beep and the red light at the bottom of the gauges lights up, but the gauges themselves don't do anything.