@uas,

Do not understand why you would even take the TomTom apart.

First you would need cold solder for any electronic units.
Using std solder will ruin any items in the TomTom.
That is why you need to use cold solder plus you need to know what you are doing.

Second see that you tried this on a Sunday when stores are closed.
Why didn't you wait till today and get the correct cable.
or
Ask a neighbor if they have the cable you need.

I find it very reckless on your part to try and take the TomTom apart and solder cables to it.

Then you go and get the car dock with a USB to the computer.

So you had a correct cable all a long.

But sorry to say you fried correspondent to the screen already.

Like Boki_Srb said buy a new one and learn from your mistakes.