What to do when macbook pro's battery starts to spurt out flame?
You punctured the Lithium Ion Battery. Basically, you created a small "short" somewhere between the electrodes inside the cell.


  A mild short will only cause elevated self-discharge and the heat
  buildup is minimal because the discharging power is very low. If
  enough microscopic metallic particles converge on one spot, a sizable
  current begins to flow between the electrodes of the cell, and the
  spot heats up and weakens. As a small water leak in a faulty hydro dam
  can develop into a torrent and take a structure down, so too can heat
  buildup damage the insulation layer in a cell and cause an electrical
  short. The temperature can quickly reach 500C (932F), at which point
  the cell catches fire or it explodes. This thermal runaway that occurs
  is known as “venting with flame.” “Rapid disassembly” is the preferred
  term by the battery industry. 1


There is an excellent video on YouTube that shows exactly what happens when you puncture one.

So, how do you dispose?

An electronics recycling center.  A simple Internet Search will bring up centers in your area.

Given your lack of experience and the high likelihood of a dangerous situation, your best bet is to let someone with skills in this sort of disassembly handle the procedure.


  am considering ask for some help from local computer repairment shops. But in case they are not able to help (since it's rather dangerous), should I give up fixing it or not?


Fix it?

You shorted out the contacts of the battery that connects it to the main board, used a chisel to pry off the adhesive from a paper thin aluminum housing and proceed to puncture the battery which caused a fire.  

If you can get the chisel out without setting it ablaze and your logic board is still functional, you still have the top case assembly to replace.  Is it worth fixing?

As for your chisel...it's a good opportunity for a trip to Home Depot.



1  Safety Concerns with Li-ion  Battery University, Last Updated 2016-09-27