GPS not connecting

[pdes]

I have a DR650GW 2 CH. For a few months, the unit has stopped recording the GPS info/position. The blue light doesn't come on (except during the boot up so the LED is working). I have upgraded the firmware (including SSD formatting). The unit is very close to a GPS repeater so the signal is very strong. A nearby radar detector and a GPS app on my phone show that the signals are many and strong.

Any ideas as to why the unit has gone "blind" to GPS?

Thanks