Weird dent near Battery Compartment in Pavilion g6

I agree with Ironsounds that that looks like slightly melted plastic. I'm not convinced it's from the battery though, as the battery looks to be along the back edge of the laptop about an inch away, and there's no damage between it and the damaged spot. I would unscrew the L-shaped part of the bottom to take a look inside and see what lies directly above/below the damaged spot. I have a sneaking suspicion your wifi card literally fried.

If the damage inside isn't too bad, you can get a new wifi card for about $15-$25. They're pretty easy to replace (assuming the connector hasn't been damaged). The only tricky part is reattaching the tiny antenna leads.

Keyboards can be a lot more work to replace, and their cost varies with the model of your laptop. Common ones can be found for as little as $20 on eBay. More rare or exotic versions can be over $100. On some laptops you just have to remove a few screws and part of the bezel, and the keyboard lifts out. Others you have to almost completely disassemble the laptop. If the wifi can be fixed, you may be better off buying an external keyboard and using this laptop as a desktop until you have enough money to buy a new laptop.