mr1100-100 won't turn on

I am unable to turn on my router. I have tried it with and without battery. With and without USB charging. I have tried to hold the reset button, the power and reset button together.
When the USB charging cable is in, the LED is illuminated faint red and turns off when unplugged. The same is true with battery inserted, the led is on and turns off when the batter is removed. I have left the charger on with faint red led overnight with no change.
Has been working ok up until now, no problems with overheating batteries yet.