TomTom One won't charge?

Hi, I have a TomTom which is 4 years old.

I always use it plugged in to the car charger and for ages it kept losing charge. I bought a replacement battery and it charged fully and worked well for a handful of times.

Now it won't even turn on and if it does its only for a few seconds before the battery light flashes and the device turns off.

Look forward to some advice.

I've tried resetting and this doesn't help.

Please help.