This battery has brought new life into my TomTom GO520T.
It was quite easy to change, 2 off small Torx 5 screws for the cover, dig your nails in to split the screen from the main body (else use a plastic widget thingy) - once you dig in work round like changing a tyre on your bike and it pops off.
Motherboard needs to come out with 4 more (slightly shorter) Torx 5 screws.
Disconnect old battery, use a Credit card (or similar plastic card) to gently prise the battery off the motherboard.
Take the window frame shaped double sided sticky tape off the old battery and use this to stick the new one in.
Plug the cable back in, fit the motherboard (4 screws), fit the back (2 screws).
job done
I saw a video on utube that helped a lot (similar model but same method).
I tried it on 1 charge and got 3 hours straight.
Nice Lithium polymer battery.
It would have been easier if the torx screwdriver was magnetic! My battery did not come with the tool but I had 1 already. I think you can also choose to buy the battery with the tool.