e7 Cycles on and off

My e7 has been working fine, but yesterday it started cycling.

It starts, loads the chart, gets the GPS fix as usual, but then turns off.

It then restarts by itself and goes through the same loop, seemingly without end.

I have checked and cleaned the connections. All seems to be in order.

Any assistance would be appreciated. I'm on the boat and need my plotter.

Cheers..Ralph