The 2100-A16 is not responding to comms commands, and the TXE and Beat LEDs are flashing at approx once per second.

This is because the power supply on the 2100-A16 is not starting up.
Check to make sure that an earth wire has not been wired into terminal 49, or the load on the 20 V power supply is not to much.
Disconnect terminals 48 and 49 to see if the fault clears.

If there is not anything connected to terminal 49, this flashing indicates an excessive current draw from some other part of the A16.