Nexus 7: micro usb port broken I have a 2012 nexus 7, its a beast of a device.
But unfortunately the usb port of the device is broken.

Is there any way I can charge the batteries my beloved nexus? I have opened it up, and removed its batteries from the wire that was attached to the socket. I have an external changer as well, I could try attaching the wires which are on the batteries to the external charger, but its a bit risky.

I know i could get the usb port &amp; headphone socket for it and replace it, but it costs 75$, if i am spending that much money on an old nexus i could go n get nexus 7 2013.

So, is there any other way I can charge the batteries of the nexus? Apart from the batteries the device works well, and I hate to see the beast of an nVidia tegra 3 go to waste like that.
You did not give details on "broken" in which way, but if it's about not charging,
or having a flaky connection when charging:

There seems to be a common problem with the micro-USB port speciffically in phones.

It is very simple, but not so simple to detect.
The problem is dust on the "back wall" of the connector on the phone.  

If you look into it, wou will just see this "wall", with no dust.
Chances are that there is dust - like fiber collected from cloth of paper in your pocket over time, but perfectly compressed by hundreds of connecting cycles. Looks just like a perfect surface (in the limited visibility situation in the socket).

So please do not make an assumption about it and give it a try - use a needle to scratch that "wall", and see how it reacts.
Next part may be easy, surprising, and fun!

(take care of unpowering the device it you use a conducting tool)